Topic: I want send a fixed transaction fee,how can I do it? (Read 1117 times)

well i always like to be a little bit creative and technical so i will gonna suggest you to use the blockchain api like http://blockchain.info/api/blockchain_wallet_api check it out you can set this api and can send btc with 0.0001btc everytime

Depends on a lot of factors...
If your transaction is a high priority transaction***, you can try not to add any fees... Altough most miners will not add your tx to a block without it having a fee, there are still some good samaritans that add zero-fee high priority transactions to their blocks.

For everyone else, there are sites like this one: https://bitcoinfees.21.co/
1) estimate your transaction size (in bytes, NOT in satoshi's)**
2) multiply by the number found on https://bitcoinfees.21.co/ , it's your own pick if you want the transaction to have a high probability of being added to the next block, or if you're willing to wait a bit longer.

Long story short: it depends on the size (in BTC) and age (in confirmations) of your inputs to determine the priority. If it's high enough, you can try a zero-fee tx, but it can take a long time to confirm.
If you can't create a high priority transaction, you should add a fee, how much depends mostly on the number of inputs and outputs of your transaction. Adding to much won't help you a single bit, adding to little might slow down the first confirmation, adding exactly enough would be ideal


BTW: i don't quite get the last part of your question: "how is it different from existing wallets?". I'm saying the OP can run bitcoind and use a json-rpc connection to create a transaction. Bitcoind is the "original". It's usually installed together with bitcoin-qt and was the first wallet. bitcoind is also the daemon that is ran by the nodes everybody relies on


** size can be estimated by: [number of inputs]*180 + [number of outputs]*34 + 10


*** priority = sum(input_value_in_base_units * input_age)/size_in_bytes
high priority = a priority above 57,600,000
source: https://en.bitcoin.it/wiki/Transaction_fees

Will lower fee delay the transaction? can fee be set to zero or is there a minimum value? if there is a minimum value than how is it different from existing wallets?

Thanks again for your advice.

Sure, you can start bitcoind on your server, and use json-rpc
https://en.bitcoin.it/wiki/API_reference_(JSON-RPC)

createrawtransaction
signrawtransaction
sendrawtransaction

Do be carefull tough, i'd strongly advice to let senior members review your code, and do elaborate testing using the testnet. If you screw things up you might really lose a lot of BTC in a very short time.

thank you.
We are developing a web site where the function contains a bitcoin transfer,the fee is determined by the user's own choice.The way you provide is achieved by human action.Is there any API to allow the client to handle by itself,when our web send a value to the client

If you use the QT (gui usually installed together with bitcoind), you can just enable coin controll features and change the fee manually...
At least, i have coin controll enabled, and when i create a transaction ("send"-tab), i see a buttom "choose" net to the current transaction fee. When i click said button, i can chose whatever fee i'd like.

If you use bitcoin-cli you can also chose your own fee by creating a transaction manually: create a raw transaction picking your inputs and outputs, and the difference between in and out is the fee. Sign this raw transaction, broadcast it with the fee of your liking... A bit harder, but still doable.

But like been said before: it's not a good idear to use a (low) standard fee, sometimes you'll grossly overpay, most of the time your transaction will take a long time to confirm (depending on the size current mempool, fees of unconfirmed transactions, transaction size and luck)!!!

I'm using the version 0.12.1 of bitcoind

it depends on what wallet you are using. let us know what wallet you are using so we can guide you on how to do it

thank you for your help.But I still want to know how to fix the transaction fee?

I wouldn't recommend it. You could send a huge transaction with that tiny fee and get your funds frozen in the mempool. Or you could even overpay. 0.0001 is pretty low nowadays.

I set settxfee=0.0001,but it seems to be calculated with /KB.Can I send a fixed transaction fee?Like I set fee is 0.0001,the transaction fee is 0.0001 also.