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Other => Beginners & Help => Topic started by: bitcoinear on October 25, 2015, 08:31:31 PM



Title: How many confirmations to be sure about a transaction?
Post by: bitcoinear on October 25, 2015, 08:31:31 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?


Title: Re: How many confirmations to be sure about a transaction?
Post by: shorena on October 25, 2015, 08:33:22 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?

I assume you mean reversed, not resolved.

1 confirmation should be fine for most deals. If you do a high value transaction you can reasonably ask for more than one.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Mickeyb on October 25, 2015, 08:36:59 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?

Like Shorena already touched on explaining, it really depends on what you are trying to buy. For most of the stuff 1 confirmation is enough. If you are buying something really valuable like a real valuable car or you are receiving or buying 100 BTCs for example, then wait for 6 confirmations. More then 6 there is no need whatsoever!


Title: Re: How many confirmations to be sure about a transaction?
Post by: LFC_Bitcoin on October 25, 2015, 08:40:25 PM
6 to be absolutely 100% safe.


Title: Re: How many confirmations to be sure about a transaction?
Post by: c-cex-finch on October 25, 2015, 08:40:35 PM
6 is a good heuristic, however 1-2 is relatively safe for low/medium value transactions. The risks decrease exponentially with increased confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: silverleafy on October 26, 2015, 02:22:17 AM
6 confirmations is super safe, and is also a completely arbitrary number that the core devs came up with several years ago. In reality, you only need 1 confirmation to be relatively safe and 3 for large transactions just to be sure. In most cases, you can accept unconfirmed transactions, although with those, you should check the fee and for any dust outputs just to make sure that it will get confirmed.


Title: Re: How many confirmations to be sure about a transaction?
Post by: VirosaGITS on October 26, 2015, 03:46:10 AM
6 confirmations is super safe, and is also a completely arbitrary number that the core devs came up with several years ago. In reality, you only need 1 confirmation to be relatively safe and 3 for large transactions just to be sure. In most cases, you can accept unconfirmed transactions, although with those, you should check the fee and for any dust outputs just to make sure that it will get confirmed.

Might be good to point out that the wallet itself typically do not let you spend coins before 3 transactions. At least the one i used so far. So it would be a good ballpark as to what is safe.

But in truth, i never had any problem with 1 confirmation, which make it too late to submit another transaction afterwards with a higher fee to create a double spending attack.

I have to agree 6 is the go to if you're talking about a critical amount of money.


Title: Re: How many confirmations to be sure about a transaction?
Post by: iram66680 on October 26, 2015, 04:18:02 AM
One confirmation is enough for daily transaction and the risk is very low. After six confirmations, the only viable method to reverse a transaction is to execute a 51% attack. You don't need 51% of the network to execute it successfully but with it, you are almost certainly going to succeed. The more the confirmation, the harder it is to reverse. It is not possible to reverse blocks before the last checkpoint.


Title: Re: How many confirmations to be sure about a transaction?
Post by: LondonTrader on October 26, 2015, 05:32:07 AM
Hi i would say...

1 confirmation for low risk or low btc amount eg coffee

6 confirmation for high risk high btc amount eg  trading on btc exchanges

Stay safe!

cheers :-)
LondonTrader


Title: Re: How many confirmations to be sure about a transaction?
Post by: Nextgen on October 26, 2015, 05:40:37 AM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?
3 confirmations is the most common figure that all the escrows of the forum tends to choose.
double spending is not possible after that...


Title: Re: How many confirmations to be sure about a transaction?
Post by: iram66680 on October 26, 2015, 05:47:20 AM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?
3 confirmations is the most common figure that all the escrows of the forum tends to choose.
double spending is not possible after that...
Double spending will always be possible even after 6 confirmations given that the attacker controls a huge portion of the network hashrate (100% success rate for 51%). It is however true that it will get more difficult after more confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: foxkyu on October 26, 2015, 07:06:25 AM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?
I think one transaction should be enough. Mostly bitcoin payment use one transaction to confirm it.

But to make sure, six transaction is much better.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Amph on October 26, 2015, 07:30:21 AM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?
3 confirmations is the most common figure that all the escrows of the forum tends to choose.
double spending is not possible after that...

there are other forms of attack that can succeed after 3 confirmations and up to evne 5 confirmations, check the weakness of bitcoin

i would wait few conf for small transactions and all the confirmation needed for big transaction


Title: Re: How many confirmations to be sure about a transaction?
Post by: medUSA on October 26, 2015, 07:45:55 AM
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved (reversed)?

Most have been said above. I want to add that 1-2 confirmations is enough under normal network conditions. A few weeks ago, didn't we have a SPV mining issue where a few pools kept mining down the invalid fork? I remember users were advised to raise the bar to 12 confirmations. I would suggest "6" to a newbie just in case.


Title: Re: How many confirmations to be sure about a transaction?
Post by: zodiac3011 on October 26, 2015, 01:33:58 PM
Usually you can trust it with just 1 confirmation. However if you are dealing with people who are acquaintance, counter-partner or dealers, I suggest 8-10 confirmations


Title: Re: How many confirmations to be sure about a transaction?
Post by: vendetahome on October 26, 2015, 02:34:49 PM
i think it is enough to get only one transaction as most gambling websites accept deposits with only one confirmation


Title: Re: How many confirmations to be sure about a transaction?
Post by: medUSA on October 27, 2015, 10:36:24 AM
i think it is enough to get only one transaction as most gambling websites accept deposits with only one confirmation

Actually, most don't. Most gambling sites allow you to start betting with your deposit with 1 confirmation, you can't withdraw your winnings until your deposit has 6 or more confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Mickeyb on October 27, 2015, 09:22:03 PM
i think it is enough to get only one transaction as most gambling websites accept deposits with only one confirmation

Actually, most don't. Most gambling sites allow you to start betting with your deposit with 1 confirmation, you can't withdraw your winnings until your deposit has 6 or more confirmations.

As far as I know you don't need even this one confirmation! I bet on sports using NitrogenSports and Directbet and they allow you to place bets with unconfirmed transactions.

It's not like you will run away until your bet (games) don't finish.


Title: Re: How many confirmations to be sure about a transaction?
Post by: iram66680 on October 28, 2015, 03:32:56 AM
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved (reversed)?

Most have been said above. I want to add that 1-2 confirmations is enough under normal network conditions. A few weeks ago, didn't we have a SPV mining issue where a few pools kept mining down the invalid fork? I remember users were advised to raise the bar to 12 confirmations. I would suggest "6" to a newbie just in case.
Yes. However, the confirmation only affected SPV clients and older Bitcoin Core clients which do not verify whether the block complies with the network rules. If you run the latest Bitcoin Core version, you would not be affected by it.


Title: Re: How many confirmations to be sure about a transaction?
Post by: techboy2 on October 28, 2015, 05:30:12 PM
I use localbitcoins.com and they require at least 3 confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: BTCBinary on October 28, 2015, 05:37:53 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?

Many exchanges use 6 confirmations to be sure that it is not a duplicate transaction. However there are other services that only use 3 and other only use 1 confirmation. But to be sure I guess you'll need 6


Title: Re: How many confirmations to be sure about a transaction?
Post by: CasioK on October 28, 2015, 07:14:32 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?

Many exchanges use 6 confirmations to be sure that it is not a duplicate transaction. However there are other services that only use 3 and other only use 1 confirmation. But to be sure I guess you'll need 6

Even 1 conformation also accepted in some services. It's solely dependent on how much risk you're ready to take. I believe waiting for 3 confirmation are moderate policy for both the parties.


Title: Re: How many confirmations to be sure about a transaction?
Post by: VirosaGITS on October 28, 2015, 09:39:31 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?

Many exchanges use 6 confirmations to be sure that it is not a duplicate transaction. However there are other services that only use 3 and other only use 1 confirmation. But to be sure I guess you'll need 6

Even 1 conformation also accepted in some services. It's solely dependent on how much risk you're ready to take. I believe waiting for 3 confirmation are moderate policy for both the parties.

When i buy games or stuff online, it typically go through instantly, but if you end up scamming them, you're the one in trouble since they have your personal information. I understand for anonymous services, waiting for confirmation is an absolute must, however.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Hugroll on October 28, 2015, 09:44:07 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?
1 confirmation is usually enough,however if you are dealing with very large numbers id be on the safe side and wait for atleast 3 confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: sana9821 on October 28, 2015, 09:54:07 PM
i believe that 2 confirmations might be enough for counting the deposit as it would be really hard to fake something with 2 confirms


Title: Re: How many confirmations to be sure about a transaction?
Post by: TTMNewsMJ on October 29, 2015, 01:05:24 AM
It will be 6 confirmations to be 100% sure.


Title: Re: How many confirmations to be sure about a transaction?
Post by: iram66680 on October 29, 2015, 02:55:48 AM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?

Many exchanges use 6 confirmations to be sure that it is not a duplicate transaction. However there are other services that only use 3 and other only use 1 confirmation. But to be sure I guess you'll need 6

Even 1 conformation also accepted in some services. It's solely dependent on how much risk you're ready to take. I believe waiting for 3 confirmation are moderate policy for both the parties.

When i buy games or stuff online, it typically go through instantly, but if you end up scamming them, you're the one in trouble since they have your personal information. I understand for anonymous services, waiting for confirmation is an absolute must, however.
Most don't actually require valid information, you can easily just input a fake information and most would just accept it. It isn't a must for most sites, in physical stores, waiting for confirmations is rarely seen.


Title: Re: How many confirmations to be sure about a transaction?
Post by: VirosaGITS on October 29, 2015, 04:44:44 PM
Hello,
how many confirmations should a Bitcoin transaction have in order to be sure that the transaction could not be resolved?

Many exchanges use 6 confirmations to be sure that it is not a duplicate transaction. However there are other services that only use 3 and other only use 1 confirmation. But to be sure I guess you'll need 6

Even 1 conformation also accepted in some services. It's solely dependent on how much risk you're ready to take. I believe waiting for 3 confirmation are moderate policy for both the parties.

When i buy games or stuff online, it typically go through instantly, but if you end up scamming them, you're the one in trouble since they have your personal information. I understand for anonymous services, waiting for confirmation is an absolute must, however.
Most don't actually require valid information, you can easily just input a fake information and most would just accept it. It isn't a must for most sites, in physical stores, waiting for confirmations is rarely seen.

In that case, i assume they are dealing with something like Coinbase which i assume cover them in case of a double spending attack?
 
However the website that i use and give the good immediately, previously obtained my personal information. I guess one way or another they are protected. For instance if its physical product, the transaction will most likely have been confirmed by the time the packaging is ready to be shipped. If its virtual good, like a game on steam, then the code could be perhaps invalidated.


Title: Re: How many confirmations to be sure about a transaction?
Post by: coinyoo on October 29, 2015, 08:05:40 PM
When i started to use Bitcoin i had a similar question. Someone told me that 7 confirmation is a must, but better when you wait until it has 20 confirmation as minimum.


Title: Re: How many confirmations to be sure about a transaction?
Post by: silverleafy on October 29, 2015, 08:09:43 PM
When i started to use Bitcoin i had a similar question. Someone told me that 7 confirmation is a must, but better when you wait until it has 20 confirmation as minimum.
7 is a bit too much. 20 is super overkill. 20 is completely unnecessary in most cases. Of course, there are exceptions like when there was a major fork back in July. But that is easily remedied by keeping your software up to date.


Title: Re: How many confirmations to be sure about a transaction?
Post by: 98problems on October 29, 2015, 08:11:39 PM
i believe that you need something like 1 confirmation as people usually cant double spend bitcoins with it


Title: Re: How many confirmations to be sure about a transaction?
Post by: Anmol_Verma on October 31, 2015, 05:04:25 AM
Bitcoin transactions need atleast 3 confirmations by bitcoin network to be fully trusted and confirmed :)


Title: Re: How many confirmations to be sure about a transaction?
Post by: Amph on October 31, 2015, 10:49:52 AM
When i started to use Bitcoin i had a similar question. Someone told me that 7 confirmation is a must, but better when you wait until it has 20 confirmation as minimum.

above 6, is not needed at all, in most case 3 are sufficient, and in some other case even 1 is okois

usually i do it based on the amount that i'm spending, the more big the more confirmations, up to six


Title: Re: How many confirmations to be sure about a transaction?
Post by: quadriple7 on October 31, 2015, 02:41:10 PM
i believe that you might be safe with one confirmation


Title: Re: How many confirmations to be sure about a transaction?
Post by: crairezx20 on October 31, 2015, 05:22:37 PM
I think 4 or 5 confirmation before we know and sure the transaction arrive soon in your wallet address.. before i got only 3 confirmation but i didnt recieve it. and its rejected by a blockchain then the bitcoin 4 day or more before the bitcoin came back to a sender...


Title: Re: How many confirmations to be sure about a transaction?
Post by: CIYAM on October 31, 2015, 05:25:55 PM
You can't be 100% certain of a Bitcoin tx until a "checkpoint" has been published (which unfortunately is a centralised thing controlled by the devs).

A blockchain "re-org" (where a better chain replaces the current one) can actually go as far back as the last checkpoint (which could be thousands of blocks).

It is extremely unlikely that such a "re-org" could happen (and has never happened so far) but re-orgs of more than 3 blocks have occurred before (the worst such problem was around 6 blocks from memory).

So you basically have to decide upon the risk you want to take in accordance to the amount you are risking.


Title: Re: How many confirmations to be sure about a transaction?
Post by: VirosaGITS on October 31, 2015, 07:11:11 PM
You can't be 100% certain of a Bitcoin tx until a "checkpoint" has been published (which unfortunately is a centralised thing controlled by the devs).

A blockchain "re-org" (where a better chain replaces the current one) can actually go as far back as the last checkpoint (which could be thousands of blocks).

It is extremely unlikely that such a "re-org" could happen (and has never happened so far) but re-orgs of more than 3 blocks have occurred before (the worst such problem was around 6 blocks from memory).

So you basically have to decide upon the risk you want to take in accordance to the amount you are risking.


This is why 6 blocks is rock solid. Even 1 block is relatively secure since the odds of anything being redone is low, and also why 3 blocks is standard. Waiting for 6 block is the sweet spot where it does not take *too* long but it is very safe.

Although at this point i am not sure what kind of event that could invalidate 6 blocks old transaction.


Title: Re: How many confirmations to be sure about a transaction?
Post by: StratusOakmont on October 31, 2015, 07:34:04 PM
i think 3+ confirmations is enough to be sure about a transaction ( higher amount ) otherwise if you are transacting low amount then 1+ should be pretty much to be sure with the transaction. :)


Title: Re: How many confirmations to be sure about a transaction?
Post by: idyu on October 31, 2015, 07:36:17 PM
3 should be very safe, i remember before localbitcoins needed 5 confirmations to confirm the deposit and that was really to much and sometimes took long.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Mickeyb on October 31, 2015, 11:11:03 PM
3 should be very safe, i remember before localbitcoins needed 5 confirmations to confirm the deposit and that was really to much and sometimes took long.

This is what I hate about Kraken. They require 6 confirmations. I don't know why they don't lower this a bit. It takes forever to send your coins to the exchange.

Then again they are very security prone. I guess that's why they still keep 6 confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: winguard on November 01, 2015, 06:15:49 AM
My local exchange coins.ph requires 3 confirmations when cashing out Bitcoin to fiat. So 3 confirmations is sufficient enough.


Title: Re: How many confirmations to be sure about a transaction?
Post by: ranochigo on November 01, 2015, 06:21:30 AM
Most transactions don't really need confirmations to be in the <50% risk range. It only needs a few seconds for it to proporgate around the network and ensure that there isn't any competing transactions. One confirmation would be secure enough to accept the transaction unless there is a block reorg. It would be back to unconfirmed. Most exchanges requires over 3-6 confirmations as losses are not a choice for them with huge trade volumes.


Title: Re: How many confirmations to be sure about a transaction?
Post by: JumperX on November 01, 2015, 08:16:26 AM
My local exchange coins.ph requires 3 confirmations when cashing out Bitcoin to fiat. So 3 confirmations is sufficient enough.

it really depends on the site if how many confirmation they needed for a transaction to reflect on your balance but atleast 1 confirmation is safe enough and that will not be able to cancel


Title: Re: How many confirmations to be sure about a transaction?
Post by: pjsonowal on November 01, 2015, 10:27:48 AM
i think 6 confirmations is enough to get sure about transactions that is 1BTC+.
On other hand 3 confirmations is enough for lower amount of BTCs.


Title: Re: How many confirmations to be sure about a transaction?
Post by: CasioK on November 01, 2015, 03:11:33 PM
i think 6 confirmations is enough to get sure about transactions that is 1BTC+.
On other hand 3 confirmations is enough for lower amount of BTCs.

Yes these are the best way of getting your bitcoin transaction most securely. But 6confirmation or 3 confirmations are best suited only with latest bitcoin core client only. If you use old bitcoin-qt client then you must wait for some 30 confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: ranochigo on November 01, 2015, 03:30:44 PM
i think 6 confirmations is enough to get sure about transactions that is 1BTC+.
On other hand 3 confirmations is enough for lower amount of BTCs.

Yes these are the best way of getting your bitcoin transaction most securely. But 6confirmation or 3 confirmations are best suited only with latest bitcoin core client only. If you use old bitcoin-qt client then you must wait for some 30 confirmations.
This applies to SPV clients too. They trust the miners without verifying the validity of the blocks.

When pools are SPV mining, they don't check the validity of the block and whether it complies with the network. Those mining pools then generate invalid blocks which get invalidated by Bitcoin core 0.10+ but not anything below or on 0.9.4 or earlier as those Core clients are not aware of the new rules. AFAIK, this isn't a threat right now. Majority of pools are mining on correct rules and creating valid blocks.


Title: Re: How many confirmations to be sure about a transaction?
Post by: RodeoX on November 01, 2015, 03:35:43 PM
I think of it like this...

0 confirmations = fast food purchase
3 confirmations = expensive dinner
6 confirmations = cool dirt bike
10 confirmations = 40 acre farm


Title: Re: How many confirmations to be sure about a transaction?
Post by: VirosaGITS on November 01, 2015, 06:19:54 PM
i think 6 confirmations is enough to get sure about transactions that is 1BTC+.
On other hand 3 confirmations is enough for lower amount of BTCs.

Yes these are the best way of getting your bitcoin transaction most securely. But 6confirmation or 3 confirmations are best suited only with latest bitcoin core client only. If you use old bitcoin-qt client then you must wait for some 30 confirmations.
This applies to SPV clients too. They trust the miners without verifying the validity of the blocks.

When pools are SPV mining, they don't check the validity of the block and whether it complies with the network. Those mining pools then generate invalid blocks which get invalidated by Bitcoin core 0.10+ but not anything below or on 0.9.4 or earlier as those Core clients are not aware of the new rules. AFAIK, this isn't a threat right now. Majority of pools are mining on correct rules and creating valid blocks.

Which also mean it does not mean if some wallets are outdated and accept some invalid blocks, the network itself will reject it, because most hashrate is pointed at the right wallet version.

Still too bad but not a threat.


Title: Re: How many confirmations to be sure about a transaction?
Post by: BitcoinBlackjack on November 01, 2015, 11:03:05 PM
Usually 1 is enough but in the case of confirmations, the more the better!


Title: Re: How many confirmations to be sure about a transaction?
Post by: ranochigo on November 02, 2015, 01:54:14 AM
i think 6 confirmations is enough to get sure about transactions that is 1BTC+.
On other hand 3 confirmations is enough for lower amount of BTCs.

Yes these are the best way of getting your bitcoin transaction most securely. But 6confirmation or 3 confirmations are best suited only with latest bitcoin core client only. If you use old bitcoin-qt client then you must wait for some 30 confirmations.
This applies to SPV clients too. They trust the miners without verifying the validity of the blocks.

When pools are SPV mining, they don't check the validity of the block and whether it complies with the network. Those mining pools then generate invalid blocks which get invalidated by Bitcoin core 0.10+ but not anything below or on 0.9.4 or earlier as those Core clients are not aware of the new rules. AFAIK, this isn't a threat right now. Majority of pools are mining on correct rules and creating valid blocks.

Which also mean it does not mean if some wallets are outdated and accept some invalid blocks, the network itself will reject it, because most hashrate is pointed at the right wallet version.

Still too bad but not a threat.
There was a change in block rules after Core version 0.9.5. Clients before that version would accept those blocks blindly so will those using SPV clients. Clients after and on that version will reject the block as invalid as it doesn't follow the rules and refuse to relay it.

A miner generated a block that doesn't follow the rule and miners that verify the blocks do not consider it as valid but those who have SPV mining on will continue mining on that chain and SPV client will follow the longest chain and accept it as valid. This was a threat for merchants accepting 1 confirmation transactions but there wasn't any attack at that time.


Title: Re: How many confirmations to be sure about a transaction?
Post by: silverleafy on November 02, 2015, 03:25:25 AM
i think 6 confirmations is enough to get sure about transactions that is 1BTC+.
On other hand 3 confirmations is enough for lower amount of BTCs.

Yes these are the best way of getting your bitcoin transaction most securely. But 6confirmation or 3 confirmations are best suited only with latest bitcoin core client only. If you use old bitcoin-qt client then you must wait for some 30 confirmations.
This applies to SPV clients too. They trust the miners without verifying the validity of the blocks.

When pools are SPV mining, they don't check the validity of the block and whether it complies with the network. Those mining pools then generate invalid blocks which get invalidated by Bitcoin core 0.10+ but not anything below or on 0.9.4 or earlier as those Core clients are not aware of the new rules. AFAIK, this isn't a threat right now. Majority of pools are mining on correct rules and creating valid blocks.

Which also mean it does not mean if some wallets are outdated and accept some invalid blocks, the network itself will reject it, because most hashrate is pointed at the right wallet version.

Still too bad but not a threat.
There was a change in block rules after Core version 0.9.5. Clients before that version would accept those blocks blindly so will those using SPV clients. Clients after and on that version will reject the block as invalid as it doesn't follow the rules and refuse to relay it.

A miner generated a block that doesn't follow the rule and miners that verify the blocks do not consider it as valid but those who have SPV mining on will continue mining on that chain and SPV client will follow the longest chain and accept it as valid. This was a threat for merchants accepting 1 confirmation transactions but there wasn't any attack at that time.
This can happen with any soft-fork, but it only happened once in July when BIP 66 activated. It is possible that that fork issue could happen again if there is another soft-fork where miners don't upgrade and are spv mining, but hopefully they all learned their lesson.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Corealz on November 02, 2015, 03:48:11 AM
I have seen alot of people wait between 3-5 transactions so I use that as a rule of thumb for my own transactions.


Title: Re: How many confirmations to be sure about a transaction?
Post by: favdesu on November 02, 2015, 09:17:51 AM
something between one and six. If in doubt, wait for three confirmations. that's what I would recommend


Title: Re: How many confirmations to be sure about a transaction?
Post by: coinyoo on November 04, 2015, 10:08:07 PM
i would say at least 2 confirmations. But better is to wait until you have 5 confirmations for small amounts. For larger amounts you should wait until at least 20 confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: bitcoinear on November 05, 2015, 08:45:26 PM
Thanks for all the answers. Now I have got a good picture of how many confirmations my transactions need in order to be save.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Miracal on November 06, 2015, 06:53:00 AM
6 to be absolutely 100% safe.
I agree. for a lesser value transaction a single confirmation has been safe enough. But like its been said for high value transaction, just to be satisfied regarding the risk of reversing, it is better to go for at least five confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: ranochigo on November 06, 2015, 06:55:21 AM
6 to be absolutely 100% safe.
I agree. for a lesser value transaction a single confirmation has been safe enough. But like its been said for high value transaction, just to be satisfied regarding the risk of reversing, it is better to go for at least five confirmations.
I wouldn't need a confirmation if it has a small value, convenience over security. Still, it is quite secure already to accept a transaction without confirmations. The risk is pretty much close to 0. Any amount of confirmation wouldn't help if an attacker has over 51% of the total network hashrate for an extended period of time.


Title: Re: How many confirmations to be sure about a transaction?
Post by: VirosaGITS on November 06, 2015, 07:00:11 AM
6 to be absolutely 100% safe.
I agree. for a lesser value transaction a single confirmation has been safe enough. But like its been said for high value transaction, just to be satisfied regarding the risk of reversing, it is better to go for at least five confirmations.
I wouldn't need a confirmation if it has a small value, convenience over security. Still, it is quite secure already to accept a transaction without confirmations. The risk is pretty much close to 0. Any amount of confirmation wouldn't help if an attacker has over 51% of the total network hashrate for an extended period of time.

Yes its not really a risk if its like buying a coffee at the starbuck. And one transaction when you are buying something on the internet should not be a big bother if its something like an full priced AAA game.

And the confirmations that "we" recommend to wait before releasing whatever products is not really about the 51% attack. Its more in case we get a rollback because a split or a bug occurred. Some transactions can disappear when that happen, it did in the past, no idea if it will happen again.


Title: Re: How many confirmations to be sure about a transaction?
Post by: ranochigo on November 06, 2015, 07:04:08 AM
6 to be absolutely 100% safe.
I agree. for a lesser value transaction a single confirmation has been safe enough. But like its been said for high value transaction, just to be satisfied regarding the risk of reversing, it is better to go for at least five confirmations.
I wouldn't need a confirmation if it has a small value, convenience over security. Still, it is quite secure already to accept a transaction without confirmations. The risk is pretty much close to 0. Any amount of confirmation wouldn't help if an attacker has over 51% of the total network hashrate for an extended period of time.

Yes its not really a risk if its like buying a coffee at the starbuck. And one transaction when you are buying something on the internet should not be a big bother if its something like an full priced AAA game.

And the confirmations that "we" recommend to wait before releasing whatever products is not really about the 51% attack. Its more in case we get a rollback because a split or a bug occurred. Some transactions can disappear when that happen, it did in the past, no idea if it will happen again.
I was referring to the 100% that LFC gave. It kind of sound like it is impossible to double spend after that.

Well, the most serious one was with the fork in 2013. The less serious one was with BIP66 but it wasn't a threat unless you use a SPV client. And yeah, you need 30+ confirmations for it to be safe when using SPV client at that time.


Title: Re: How many confirmations to be sure about a transaction?
Post by: coinyoo on November 06, 2015, 06:09:55 PM
This is a great list ;D I bookmarked your post. One question remains. Why 0 confirmations? Wouldn't it be completely risky not waiting until it achieved at least one confirmation?

I think of it like this...

0 confirmations = fast food purchase
3 confirmations = expensive dinner
6 confirmations = cool dirt bike
10 confirmations = 40 acre farm


Title: Re: How many confirmations to be sure about a transaction?
Post by: NETFix on November 06, 2015, 08:46:56 PM
i'm not sure about it technically but most sites require at least 1 confirmation to use the site and withdraw, some require 3-6 confirmations.


Title: Re: How many confirmations to be sure about a transaction?
Post by: 23dzmaz on November 07, 2015, 12:12:44 AM
maybe 5/6


Title: Re: How many confirmations to be sure about a transaction?
Post by: ranochigo on November 07, 2015, 01:43:51 AM
This is a great list ;D I bookmarked your post. One question remains. Why 0 confirmations? Wouldn't it be completely risky not waiting until it achieved at least one confirmation?

I think of it like this...

0 confirmations = fast food purchase
3 confirmations = expensive dinner
6 confirmations = cool dirt bike
10 confirmations = 40 acre farm
Nope. In fact, I feel that 0 confirmation is safe for less than $500 as long as it fits a few criteria.
1. Inputs must not be unconfirmed
2. Transaction has a reasonable fee/kb
3. There isn't any competing transactions
4. The mining pools and nodes at geographically distributed areas have seen it.

Most mining pools do not accept transactions with spent inputs and would include whichever transaction appeared first. Also, majority of network has Bitcoin Core as their client. They relay which ever transaction came first and would ignore any other transactions with spent input in their mempool. Of course, you can ask a miner to mine the double spend for you but it isn't worth it for less than $500.


Title: Re: How many confirmations to be sure about a transaction?
Post by: Christyfrazier on November 21, 2015, 08:46:20 AM
Hi,

1 confirmation for low risk or low btc amount

6 confirmation for high risk high btc amount

Thanks


Title: Re: How many confirmations to be sure about a transaction?
Post by: coinyoo on November 21, 2015, 09:55:09 AM
OP, please close this topic. The question has been answered and all new answer are just copies of the others.

Hi,

1 confirmation for low risk or low btc amount

6 confirmation for high risk high btc amount

Thanks



Title: Re: How many confirmations to be sure about a transaction?
Post by: jaberwock on November 21, 2015, 12:08:59 PM
you are only sure when blockchain.info site doesn't show the number of confirmations(I think after 100 confirmations)

But every confirmation makes more and more unlikely some kind of doublespend. At the point of being in practice impossible. After 3 I think the risk is 0 no matter the value.

I'm still to know about some doublespend of a transactions that got 2 or more confirmations.