Bitcoin Forum

The other day I made a transaction of 0.01 BTC and instead of the default transaction fee 0.0005 BTC I entered 0.0002 BTC. The transaction went fine and I believe it took as long to arrive as with the default transaction fee.

What is the minimum transaction fee I can pay? And what could possibly happen if it is too low?

The minimum fee possible is 0, however it depends on many different factors.

I suggest reading this article: http://bitcoinfees.com

The minimum transaction fee is 0BTC.
This transaction just takes longer (from a few hours to a few days).

Is there a risk that it never arrives? Could I respend it if it doesn't arrive?

No, it just takes some tiem :)
And you can't double spent.

I have to disagree with Cryptocat:
Yes, there is a chance that it will be stuck for a very very long time, especially if you are sending a tiny amount of BTC.
It is possible to double-spend the Bitcoins and the first one to be accepted in a block will come through.
(the same client won't let you make a second transaction, you could import the private key to a second one or use some program to edit a local client)

Is the transaction time possible to predict based on the transaction fee? And is it possible that a transaction with a fee of 0 BTC gets handled right away if there is a low number of transactions in the network?

The transaction time is based on the integration of your transaction into a newly mined block.
Miners will prefer transaction with a higher fee (+some other factors like coin age, amount of Btcs,datasize), so they will include them first.
If there is a low number of transactions your transaction without a fee may be handled right away.

Btw: usual transaction fee of the qt-client is now 0.0001 (unless the Btc amount is made up by a lot of tiny transactions. If you collect dust from the free BTC sites and try to send all that the transaction will have a very big datasize)
You should be fine by using that fee.

You should listen to Birdy  ;D

I sometimes sent some BTC from my blockchain wallet without fees.
They took some time, but they always arrived.

The fee amount usually varies, but its never very high and usually isnt over 1%

1 satoshi per kb should bé enough to start à little experiment, then up it to 1000 satoshis see what happens.

If i am correct anything under 0.01 is about 0.0005 a fee
If you have a lot of small satoshi causing it to have a lot of memory or something you could get a fee of 0.0195 or something (meh o.o)

if transaction = 0.01BTC and fee = 0.0005BTC, fee = 5%

The default answer is now ฿0.0001/kb for Bitcoin-qt 0.8.2 and up. But, in reality, miners charge whatever they want. If evil mega-Corp buys a ton of ASICs (or miners collude) and controls nearly all the hashing power....they set the true minimum fee.

0.8.2 Release notes
===================

Fee Policy changes
------------------

The default fee for low-priority transactions is lowered from 0.0005 BTC
(for each 1,000 bytes in the transaction; an average transaction is
about 500 bytes) to 0.0001 BTC.

Payments (transaction outputs) of 0.543 times the minimum relay fee
(0.00005430 BTC) are now considered 'non-standard', because storing them
costs the network more than they are worth and spending them will usually
cost their owner more in transaction fees than they are worth.

Non-standard transactions are not relayed across the network, are not included
in blocks by most miners, and will not show up in your wallet until they are
included in a block.

The default fee policy can be overridden using the -mintxfee and -minrelaytxfee
command-line options, but note that we intend to replace the hard-coded fees
with code that automatically calculates and suggests appropriate fees in the
0.9 release and note that if you set a fee policy significantly different from
the rest of the network your transactions may never confirm.

You can double-spend

Whilst it is *possible* it is actually in practice rather difficult to do (I tried once after making a huge mistake with fees doing a raw tx).

Any node that has seen the first tx will ignore the "double spend" attempt - making it virtually impossible to then do so after only a few seconds across much of the network.

Indeed, you can't do this immediately but the saying "you can't double spent" leads newbies to fear/feeling scammed/posting aggressively in the tech forum.

So:
Yes we can.
But you'll have to use the search function to find the guide and to wait a bit.

Actual recomended fee is 0.0001BTC

I agree with the sentiment (too much FUD spread around in general) but at the same time it should be understood that the entire *premise* of Bitcoin was to "solve the double spending problem" (so IMO not really a useful thing to tell people that you "can double spend" as it then leads people to infer that Bitcoin is *fundamentally flawed* which is isn't).

Indeed, I used the same words than the post I replied to
That would be nice to find another word for this

For newbies: double-spending means here 'replace an old, stuck transaction which isn't accepted in the blockchain with a new one'

Per 1kB of transaction.

That's seems more reasonable, around a penny per transaction.  Remember some will send 10's, 100's, or more of transactions a day.

This also depends completely on inputs and outputs. Say you have 100 inputs and 10 outputs, this will cost 0.0019 BTC if all inputs do not have sufficient age for a speedy transaction. This generally only happens if the amounts you received are fragmented or for very large transfers. The actual formula is:

(inputs * 180) + (outputs * 34) + 10 ± inputs

where inputs is the # of inputs and outputs the # of outputs that are not of sufficient age.

By the way, I've had http://bitcoinfees.com updated recently, including changing the default fee from 0.0005 to 0.0001.

How much is sufficient age?

I created a spreadsheet that tells you whether you need to pay a fee and how much it will be:

http://bitcoinspakistan.com/files/2013/08/Bitcoin-Transaction-Fee-Calculation.ods_.zip

It's a Libre Office Calc spreadsheet.

Sorry for the offtopic, but I’m curious why your website only has English version and no Urdu version?

English is one of the languages of Pakistan. Most Pakistani websites are in English.

This is a good place for it, its based on the BTC value, age, and size in bytes of the inputs. https://en.bitcoin.it/wiki/Transaction_fees#Technical_info

Basically, the formula is priority = sum(input_value_in_base_units * input_age)/size_in_bytes where input_value_in_base_units is equal to satoshis (where 0.01 is 1,000,000 satoshis) and the input_age is the number of confirms. The size is 180 ± 1 for each input. If the priority is greater than 57,600,000 than the input/inputs are of sufficient age. The wiki page might explain this better than I can.

i do 0.00011 because its just a little bit above the minimum. i get included in the next block every time.

If you click on your transaction hash in blockchain.info it will tell you your priority and a guess of when it'll be mined.

You know what I really miss?
This:    bitcoincharts.com/bitcoin/txlist     (Don't bother visiting it, it's now 404).

I remember that page really started to get crazy once there were more than about 2000 unconfirmed transactions, but it was really good for seeing the progress of each transaction up the priority queue.

Can anyone early-adopter enough to remember that page point me to the current equivalent (if one exists)?

Edit: I found this http://blockchain.info/unconfirmed-transactions?show_adv=true but IMHO it's nowhere near as good as the old bitcoincharts one - it doesn't even show the priority number.

Cool.

The minimum fee possible is 0 ;D

has anyone tried using an negative fee value? :o

when you make a transaction fees are a product of the difference between the inputs and the outputs. so the idea of a negative fee would mean trying to claim that you had more bitcoins in your outputs than in your inputs. it would be rejected by the network on the grounds of ridiculousness.

What's the minimum non-zero fee that makes sense? I mean, 1 satoshi is not treated by almost all nodes as a "proper" bitcoin transaction fee. The minimum non-zero fee used to be 0.0001 BTC per 1 kb, but how has 0.8.6 or 0.9+ affect this?

I don't know much about the theory, but currently, the minimum generally accepted non-zero fee seems to be 0.0001 (ie, about 8 cents). Of course, this depends on the transaction size as you said.

The chainsnort tool is your friend if you want to see what people are generally paying for their transaction fees (last column):

https://bitcointalk.org/index.php?topic=373490.0

https://i.imgur.com/nlCkLdv.png

What is the minimum now? I've heard about a limit of 5360 sat per transaction.

Minimum is is 0.15 but it depends how much BTC/etc you will transact (the higher Coins the higher fee).

What happens if a fee is set so low that the transaction is not confirmed within weeks or even months. Is it possible for a transaction to wait years (especially with the current number of transactions and the fees)? Is no way to cancel such a transaction?