What fee should I use for my very large transaction?

[aj5577]

I have a wallet on blockchain.info. I am using their API to do a "send to many" transaction. I am sending bitcoin from my wallet to about 3000 addresses. Around 200USD to each address. I was told that a send to many is counted as a single transaction, not 3000 separate transactions ( true or false? ).

I want to know what an optimal fee to use is so this transaction does not get stuck in limbo or go very slow.

Thanks!!!!

[hexafraction]

You can use http://www.mocacinno.com/page/feeestimate to estimate the necessary fee. Although a send-to-many is a single transaction, it is larger than a transaction to a single address, due to the fact that each of the 3000 addresses is an output of the txn. Figure out how many inputs you need (outputs=3000) based on the current unspent outputs available in your wallet.

Anyway, if you're dealing with 3000*200=600 000 USD, you should probably use a more secure wallet than blockchain.info. Ideally, you'd use a secure hardware wallet (such as Trezor with proper backups/safeguards) or a cold offline wallet.

[aj5577]

I'm really lost on figuring out inputs and outputs, and how many bytes my transaction will be.

There is an API at https://bitcoinfees.21.co/api which will give a estimate of the "fastest fee" but it is measured in satoshi per byte. Again how do you know how many bytes the transaction will be??

[HCP]

The basic formula is: TX Size = (#Inputs * 148) + (#Outputs * 34) + 10

Outputs is easy... basically how many addresses are you sending to? You said 3000... so that part is sorted.

For the inputs, you would need to see how many UTXOs you currently have in your wallet... and figure out the minimum number of UTXOs that you would need to use to get to the required amount you need to send + fee.  Unfortunately, I can't see any API call that would assist with this part... so you'd need to go through your wallet manually to figure it out. For each UTXO you need to use, that equals 1 input. So, if you needed to use say 20 UTXOs to get to the required amount, you'd have 20 inputs.

Then you can just pop those two numbers into mocacinno's fee estimate, Option #2 and click estimate...

[aj5577]

When I go to my wallet and click "addresses" it shows 0. This is on blockchain.info.

Is that normal? I never receive money with this wallet hence the zero addresses I suppose.

[HCP]

So how exactly are you intending on sending out a total of 266.55 BTC, split across 3000 addresses if you have no bitcoins in your wallet?

[aj5577]

Oh I didn't think about this all the way through, I just looked at the display in the wallet ( shows 0 address for some reason ).

But since I did receive the initial deposit it has to have at least 1.

So I'd do the estimation as 1 input and 3000 outputs?

[zupdawg]

Oh I didn't think about this all the way through, I just looked at the display in the wallet ( shows 0 address for some reason ).

But since I did receive the initial deposit it has to have at least 1.

So I'd do the estimation as 1 input and 3000 outputs?

is that initial deposit in only 1 transaction? if yes then you are correct, 1 input and 3000 outputs. tho, you can give us the address you are planning to use so we can help much further about the number of input

[aj5577]

So I was messing with the estimation tool. I guess if you are sending small amounts of money then the fees will kill you.

For example say I was going to send $1usd to 17 people from a single address ( 1 input, 17 outputs ).

The recommended fee to get into the next block is $4. So a $4 fee to send $17. That's pretty high percentage wise.

Is bitcoin designed to only send large amounts to single outputs ( the fee for sending a million dollars to one address would be a few cents - 1 input 1 output ).

Little payments I guess are discouraged?

[HCP]

That is a transaction size of:

148 + (17 * 34) + 10 = 736 bytes. Given that a "standard" (1 input, 1 output + change address) transaction is ~226 bytes, you've effectively managed to send 17 transactions for the price of sending to 3(.25)

Send to many is definitely a great option.

Honestly, with the way the network is overloaded and "recommended" fees being so high... if you are wanting to do little micro payments, need fast confirmations and are getting all anxious about "high fees", you may as well go use altcoins like DOGEcoin or Litecoin or something...