How many wei in 1 ETH? Why is gas priced in gwei?
Ethereum has seven different names for the same currency: from wei (the smallest, like a cent, but a quintillion times tinier) up to ether (the number you see in your wallet). In between: kwei, mwei, gwei, szabo, finney. Developers code in wei. The network quotes gas in gwei. You look at your wallet in ether. Three different units for the same amount, easy to get lost.
Type any value in any field, the other six update live. No rounding, no precision loss (we use BigInt math, the same way Ethereum itself does).
Plus ready-made scenarios: cost of a basic transfer (21,000 gas × 30 gwei), what 1 finney is in gwei, the total for 100 transactions. Click, get the answer. Optional: enter the ETH/USD rate manually to see every unit in real money.
How to use it
- Type a value into any field (e.g. 30 in the gwei box, or 0.0021 in the ether box), the other six fields will show the same amount in their own unit instantly.
- Click a preset, e.g. *"Basic transfer (21,000 × 30 gwei)"* fills in the total fee and shows what it is in ETH and wei.
- Aliases under each field (babbage, lovelace, micro, milli): these are historical names from the original Ethereum whitepaper. Almost nobody uses them today, code uses wei or gwei, humans use ether.
- ETH/USD rate is entered by hand, the calculator shows what each unit is in real money. We don't fetch rates from the internet (zero external requests, the tool works fully offline).
- The wei field can show huge numbers (e.g. 1 ETH = 1,000,000,000,000,000,000 wei), that's normal. The network counts this way to avoid rounding bugs.
When this is useful
Six typical situations where this converter gives you a concrete answer:
- Writing a smart contract. The function takes a value in wei, but you think in ether. The converter turns 0.05 ETH into 50,000,000,000,000,000 wei in a second, paste it into your test and move on.
- Checking whether a transaction fee is high. Your wallet says: 0.0021 ETH. Type it in → you see 2.1 million wei, 2,100 gwei, plus the USD equivalent. Turns out it's a few dollars. Decision: wait for cheaper.
- Explaining Ethereum units to a teammate. You show: 1 ETH = 10^18 wei. They ask: *"what's gwei?"*, type 1 gwei and you both see: 1,000,000,000 wei, 0.000000001 ETH. Three clicks instead of 10 minutes of hand-waving.
- Estimating the cost of 100 transactions in your app. Each uses 21,000 gas and the network is currently charging 30 gwei per gas. Multiply: 21,000 × 30 × 100 = 63,000,000 gwei → the converter shows 0.063 ETH. Multiply by the rate → you have an annual budget.
- Reading API docs. The example shows value: 1000000000000000000. Paste it into wei → you see 1 ETH. Aha, that's all. No counting zeros in your head.
- Setting a max fee (max gas price). You want to pay no more than 50 gwei per gas. Convert: that's 0.00000005 ETH per unit. Multiply by 21,000 gas = 0.00105 ETH total. Now the numbers in your wallet finally make sense.