Web3 Lab · T.01
ETH Unit Converter
Wei ↔ Gwei ↔ Ether — exact BigInt math, no rounding errors. Type in one field, the rest follows live.
This converter needs JavaScript (runs locally in your browser).
Gas cost calculator
The five units that matter
Ethereum only counts in Wei (integers) internally. Gwei is the gas unit, Ether the trading unit — in between sit Finney (milliether) and Szabo (microether). Rule of thumb: 1 ETH = 10³ Finney = 10⁶ Szabo = 10⁹ Gwei = 10¹⁸ Wei.
| Unit | Wei | Typical for |
|---|---|---|
| Wei | 1 | Protocol, x402 micropayments |
| Szabo | 1,000,000,000,000 | Microether, tiny amounts |
| Finney | 1,000,000,000,000,000 | Milliether, common in early days |
| Gwei | 1,000,000,000 | Gas price (e.g. 21 Gwei) |
| Ether | 1,000,000,000,000,000,000 | Amounts, balances |
Bridge to agent payments: What happens when AI agents pay for themselves — settled in the smallest units, convert them right here.
Frequently asked questions
How much Wei is 1 Ether?
1 Ether = 1018 Wei = 109 Gwei. Just type
1 into the Ether field above.Why BigInt instead of normal numbers?
JavaScript
Number rounds beyond ~15 digits. 1018 Wei plus decimals only works exactly with integer arithmetic (BigInt).Can I share via link?
Yes — the URL carries
?value=…&unit=…, e.g. ?value=21&unit=gwei. Just copy and send it.Does my input leave the browser?
No. No backend, no tracking on this page — purely local math.
What does a simple transfer cost?
Gas price × 21,000 — e.g. 21 Gwei × 21,000 = 0.000441 ETH. Calculate live in the gas cost calculator above.
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