Getting to grips with fractional amounts of ETH with lots of zeros after the decimal point can be a real chore. This is what makes Gwei so handy.

A Gwei is a measure of small amounts of ether (ETH), the Ethereum blockchain’s native currency. You’ll see and hear Gwei mentioned frequently in relation to ETH because it makes discussions about gas a lot more comprehensible. All work on Ethereum is priced in Gas, and the system behind it calculates how much someone should be paid for performing a transaction or for doing something that’s required by a smart contract.

A Gwei is one-billionth (or one Nano) of an Ether. This means that one Gwei is equal to 0.000000001 or 10-9 ETH, and that one ETH is equal to one billion (109) Gwei.

There are quite a few other denominations of ether, and each one represents a multiple of wei (the smallest ETH unit):

UnitWei ValueWeiEther Value
Wei1 wei110-18 ETH
Kwei10 wei1,00010-15 ETH
Mwei106 wei1,000,00010-12 ETH
Gwei109 wei1,000,000,00010-9 ETH
Microether1012 wei1,000,000,000,00010-6 ETH
Milliether1015 wei1,000,000,000,000,00010-3 ETH
Ether1018 wei1,000,000,000,000,000,0001 ETH

You can try thinking of it this way: as ETH is to the US dollar, so Gwei is to cents (although it’s a billionth rather than a hundredth). It’s ideal for measuring fractional values of the whole currency unit in a way that’s easier to comprehend, so calculating the gas price becomes much more straightforward.

If you hear terms like a Shannon, NanoEther or Nano then they’re still talking about Gwei. These are just alternative names. Shannon comes from the mathematician and cryptographer, Claude Shannon, who is recognized as a pioneer of Information Theory.