Bitcoin Forum

I was taked payment on btc . i want konw How many confirmations does it take to verify the deposit / not refund client ?
thanks

With 1 confirmation, there is 50/50 chance of a double spend is possible.
Every confirmation reduces that chance significantly

I would take 1 confirmation as received payment if amount is small, and may be 2 or 3 for 1 btc and above. I would say 6 confirmations is extremely safe against double spending attempts.

1 confirmation should more than suffice for small amounts

i have seen most peoples and exchanges want atleast 3 confirmation

After 3-4 confirmation
So go for 4

Minimum number of 3 confirmations is enough to verify deposit.
Some services / exchanges use 6 confirms.

i think it also depends on the amount of the transaction. for example, with a transaction under 5 btc, then 3 confirmations is good. if the transaction is over 1000 btc then 6 confirmations would be safe to verify the deposit. if the transaction is < 1 btc then i'd say 1 confirmation would be enough.

In China, most gambling/exchanges demands 1 confirmation, one is enough.

1 confirmation in enough and non doubled able anyways if you want to be more safe and secure wait for 3 or 4 confirmations

Sometimes, transactions with no confirmations that are relayed well over the network can be effective enough to prevent doublespending. For safety reasons, 3-6 confirmations are usually required by exchanges dealing with high volumes. You may want to implement bitpay to simplify things.

It depends on the transaction amount.
For low value transactions, 1 confirmation is enough.
Double spend is considered next to impossible if there are 6 confirmations.

Like most mentioned, it only takes 1 confirmation to update the balance to show.

But waiting for the confirmation can take awhile or little as like 5 mins.

Depends on the amount, as well. When selling someone a coffee I may not even require a single confirmation, just seeing the network accepted the transaction and maybe listening for attempted double-spends is enough. For $10-$100 I'd wait 1-2 confirmations, for $100-$1000 3-4 confirmations, and $1000-$5000 5 confirmations. Above than I think 7 or so.

1 to 6 based upon the amount

until 3 there is still chance of double spending, there are other attacks besides 51%, i would say 5, to be safe

to just verify you need 1

Most services and clients prefer 3 confirmations before flagging a transaction complete. It is safe to say that 3 confirmations are enough to avoid double spending.

One confirmation is good, 2-3 confirmations is even better

I just watch my multibit wallet when it shows "spendable" for the amount i just received, so i am sure that this amount is ok received.

When I transact with Coinbase, payment or withdrawal or deposit, they recommend 3 or more confirmations.  

If you're talking about something smaller like $5 or less, I would wait for the 1 confirmation and be on my way.

usually 1 confirmation but there is also necessitated 6 confirmation
but 1 confirmation its good enough :)

Always wait for 5 confirms. That's my restriction.

if you want to be more secure and safty, you have to wait for 3 or 4 confirmations.

I tend to wait for 6 confirmation, just to feel safe.

as it was already written it mainly depends on the amount you want to send/receive. Time is another factor.
Exchanges most typically use 3 confirmations to avoid double spending.
I would recommend anything between 3 and 6 as a reasonable value.

6 confirmations for full assurance

Just wait after 4-5 confirmations  8)

Transactions can be reversed even after 6 confirmations. Dont take it as a insurance. If one entity controls 51% of the hashrate, he could execute and attack which would allow him to reverse transactions with 6 confirmations and above. However, the more confirmations it has, the lesser chance it can be reversed. The problem is most people can't afford to wait for 6 confirmations. Which can take up to one hour or maybe 2.

what if I waited under 6 confirmation? what it does not feel safe?

That depends largely on the amount that you are receiving. For anything worth a mere few buck, I would say 2 confirmation is likely more than enough. For an attacker it's not worth trying to force a double spend and cheat with that such small amount. For large transactions, the safest is 6 confirmations.

Well, just 'feel'. Of course I know it can be secure or insecure under 6 confirmations.

As I already wrote (see my post above), it depends on two factors: how much BTC you transfer and time pressure. The longer you wait (and thus more confirmations you have) the less likely is that the transaction can be reversed.

It is pretty hard if a transaction is left in the open for sometime and has been propagated well. It prevents the most simple type of attack without confirmation. If you have one confirmation, it is nearly impossible to double spend without 51% of hashrate. For larger amounts, more confirmations would be recommended.

At least 3 confirmations to avoid double spending
many exchange will be credited after 3 confirmations on the Bitcoin network.

One confirmation would typically stop any double spending. However, doublespending cannot be avoided unless it has a lot of confirmations. More blocks just reduces the risk of double spending.

At least 5 confirmations, to be on the safe side.

only one conformation is enough. but depending on the amount and the service you might use, they sometimes require more confirmation upto 5 times

aslong as you dont do very big trades , 1 confirmation is above enough :) to be extremly safe go for 10-15 + ( 100 btc + ) or maybe you're just very safe about your coins.

saying that you're on the safe side with 5 confirmations , is like saying 20% is considered safe. '-'

I'm fine with transactions being registered by blockchain.info, blockr.io, etc. and don't wait for confirmations, usually. I don't believe a double-spend is that easy. But you should set your limit according to your own risk-assessment.

3 confirmations are fine but there's hardly a chance of double spend

Why do exchange go for 3-4 confirmation even on small amt?

Exchanges probably wouldn't bother making a script that checks for amount and see how much confirmations does it need. It is much more convient to use a flat amount of confirmations.

I think it would be best to wait for 3 confirmations even for transactions <1 btc. For transactions > 4 btc then 6 confirmations will be enough. That's just what I'd do.

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