Ethereum Unit Converter
Instantly convert between Ether, Gwei, and Wei with exact precision for Web3 transactions.
Ethereum has no decimals at the protocol level — everything is an integer count of Wei, the smallest indivisible unit. Ether and Gwei are just human conveniences layered on top. If you are writing contracts, reading transaction data, or debugging a failed transaction, you need to move between them fluently.
The three units you actually need
One Ether is 10¹⁸ Wei. That is a 1 followed by eighteen zeros — a number so large it exists purely so that Ethereum never has to touch floating-point arithmetic, which would introduce rounding errors into money. Gwei sits in the middle at 10⁹ Wei, and exists for one reason: gas prices. Quoting gas at '30 Gwei' is readable. Quoting it at '30,000,000,000 Wei' or '0.00000003 ETH' is not. The rule of thumb: humans talk in Ether, gas is quoted in Gwei, and every smart contract on the network thinks exclusively in Wei. When your contract call fails with a confusing amount, it is very often because a conversion was missed somewhere in that chain.
The conversions
1 Ether = 1,000,000,000,000,000,000 Wei (10^18)
1 Ether = 1,000,000,000 Gwei (10^9)
1 Gwei = 1,000,000,000 Wei (10^9)
Ether → Wei : × 10^18
Gwei → Wei : × 10^9
Wei → Ether : ÷ 10^18There are other named units — Kwei, Mwei, Szabo, Finney — but in practice nobody uses them. Ether, Gwei, and Wei cover essentially everything you will encounter.
Working with Ethereum units
- 1In JavaScript, never do Wei math with regular numbers. Values above 2^53 lose precision silently, and Wei amounts routinely exceed that. Use BigInt, or ethers.js parseEther and formatEther.
- 2Gas prices are always Gwei. Contract values are always Wei. Mixing them up by a factor of a billion is the single most common Web3 beginner bug.
- 3When a contract expects 1 ETH, it expects the integer 1000000000000000000. Passing 1 sends one Wei — a functionally worthless amount that will usually make the transaction revert in a confusing way.
- 4Wei has no decimals, ever. It is an integer by design. If you are seeing a decimal Wei value, something has already gone wrong upstream.
- 5Reading raw transaction data on Etherscan shows Wei. Paste it here to see what it actually means in ETH — much faster than counting zeros.
Frequently asked questions
Why does Ethereum use Wei instead of decimals?
Because floating-point arithmetic produces rounding errors, and rounding errors in a financial system are unacceptable. By making every value an integer count of the smallest unit, Ethereum guarantees exact arithmetic. The same reason Bitcoin counts satoshis.
What is Gwei used for?
Gas prices, essentially exclusively. When a wallet says a transaction costs '25 Gwei', it means 25 Gwei per unit of gas. Multiply by the gas units used to get the total fee in Wei, then divide by 10^18 for ETH.
Who is Wei named after?
Wei Dai, a cryptographer who published 'b-money' in 1998 — a proposal for anonymous distributed electronic cash that predates Bitcoin by a decade. Satoshi cited it in the Bitcoin whitepaper. Naming the smallest unit after him is a nod to that lineage.
Do other tokens use the same units?
Not necessarily. ETH uses 18 decimals, and most ERC-20 tokens follow that convention. But USDC and USDT use 6 decimals, and WBTC uses 8. Always check a token's decimals() value before converting — assuming 18 for USDC will be wrong by a factor of a trillion.
Is this converter exact for very large numbers?
It handles the standard ranges you will encounter accurately. For contract-level work with maximum precision, use BigInt in your own code rather than any browser calculator — including this one. This is for reading and sanity-checking, not for generating production values.