I know this one has been asked many times before and I think I get it, but I just need a little more clarification.

At the moment, https://ethgasstation.info shows the following gas prices

Safe Low 1 gwei
Standard 5 gwei
Fast     8 gwei

So, I get that those are the recommended gas prices depending on how fast I want my transaction to be processed.

My question is regarding the gas limit. On this post, Questions about some details on Ethereum transfers and Gwei it mentions that a simple transfer will always be 21,000 gas but then later says gas limit is 21,000 + additional gas needed by the contract.

All I want to do is move some ETH from my wallet to an exchange, so does a simple transfer need any additional gas or is the original statement that 21,000 is enough true?

Am I right in thinking that if I use a limit of 21,000 at a price of 1 gwei to move ETH from my wallet to an exchange, it should go through in around 30 minutes?

The thing that concerns me about the limit is, if I don't specify enough, the transaction won't complete and I'll just lose the gas I've paid.

Thanks for any advice you can give.

1 Answer 1


You should probably use more than 21,000 gas, as the exchange wallets are usually smart contracts. They execute code, like logging an event, so the exchange gets notified whenever you deposit ether. If there's not enough gas, you'll lose all of it, without any result. If there's too much gas, however, you'll get the excess back.

As for the gas price: 1 gwei should be fine, but it won't be a fast transaction

  • Thanks Henk. Is there any rule on how much extra gas will be needed or does it differ from exchange to exchange? I'm looking at moving some ETH to Kucoin. Do you always get all the extra back so if I set my limit as 30,000 and it takes 24,000 I'll get 6,000 back or if I set the limit at 50,000 and it takes 24,00 I'll get 26,00 back?
    – Damian
    Jun 26, 2018 at 13:16
  • Yes, you'll always get the extra back. To get an indication of the gas cost, you could use MetaMask. It will estimate the amount of gas you will need for you.
    – Henk
    Jun 26, 2018 at 13:36

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