[Ethereum] ERC20 Transaction Fee – setFeeCurrency

feestransactions

Hi i now read everywhere that a transaction fee has to be paid in ETH.

But I also found via the ethereum page the following page:

https://github.com/ethereum/wiki/wiki/Standardized_Contract_APIs#data-feeds

where it says

setFeeCurrency

setFeeCurrency(address _feeCurrency)

Sets the currency that the fee is paid in

The latter two methods are optional; also, note that the fee may be
charged either in ether or subcurrency;

So is it finally possible to create an ERC20 Token that is able to transfer its tokes and is paid in the token itself? If so, is there an example contract somewhere or do I just have to add it into the constructor? If so what exactly has to be the _feeCurrency variable? The AdminAddress of the contract?

Best Answer

Transaction fee on Ethereum is called Gas and is paid to the miners for the processing power they spent on the function call, here being ERC20 transfer(). Tokens on miner's level don't have any value and does not mean anything, rather than just a state change in a smart contract. Gas can only be the same coin/token that the blockchain is using to incentivize the miners, so here on Ethereum blockchain Gas is Ether.

To understand more of this concept you can read here: https://ethereum.stackexchange.com/a/62/3157

Related Solutions

ERC20 Tokens – Paying Transaction Fees with Tokens

It is not really true at the moment that you can pay fees in anything except ETH, although there is some discussion about changing this. The way things normally work, you have to pay the fee in ETH. When you sent REP to the exchange you probably used ETH in your own account to deposit tokens in the exchange, and the exchange would have paid for the transaction to send them back out.

In theory, since it's up to the miner whether they include your transaction, you could send a low or zero fee in ETH and have a separate arrangement with a miner where you would give them some ERC 20 token, or send them USD via PayPal, or FedEx them a chicken. This depends on the miner thinking what you are giving them is valuable and being prepared to accept it as payment. If you've sent them a chicken but they don't want one, or you've sent them an ERC 20 token that they've never heard of and don't consider valuable, you shouldn't expect them to mine your transaction.

Update (Dec, 2021): Since EIP1559, the account must hold ETH to pay the fee at the time it is included in the block, and most of this ETH is burned (disappearing, to the benefit of anyone holding ETH whose ETH become proportionally more valuable) rather than being given to the miner. It is still technically possible for a miner to include a transaction from an account with no ETH at the time of sending, but they will have to add a transaction before it crediting the account with the ETH required to pay the fee.

[Ethereum] How to calculate transaction fee

What is Gas?

If you are unclear on what gas is, I recommend reading the answers to the StackOverflow question "what is gas?" before going any further.

Calculating the Transaction Fee

The total cost of a transaction is the product of the gas limit and gas price:

(gas limit x gas price) = transaction fee

In web3js the following methods are available:

web3.eth.estimateGas to estimate the gas limit
web3.eth.getGasPrice to estimate gas price

As an example, if you want to transfer all of your ether you first need to calculate the transaction fee, subtract that from the balance, and then do the transfer:

var sender = web3.eth.accounts[0];
var receiver = web3.eth.accounts[1];
var balance = web3.eth.getBalance(sender);
var gasPrice = web3.eth.getGasPrice(); // estimate the gas price

var transactionObject = {
  from: sender,
  to: receiver,
  gasPrice: gasPrice,
}

var gasLimit = web3.eth.estimateGas(transactionObject); // estimate the gas limit for this transaction
var transactionFee = gasPrice * gasLimit; // calculate the transaction fee

transactionObject.gas = gasLimit;
transactionObject.value = balance - transactionFee; // set the transaction value to the entire balance, less the transaction fee

web3.eth.sendTransaction(transactionObject, myCallbackFunction);