Gwei (gigawei) is 10^9 Wei, or one billionth of an ETH. It is the standard unit for Ethereum gas prices. For example, a typical gas price of 20 Gwei means 0.000000020 ETH per unit of gas.

Wei is the smallest denomination of Ether, named after Wei Dai. 1 ETH = 1,000,000,000,000,000,000 Wei (10^18). Smart contracts work internally in Wei to avoid fractional numbers.

Why does precision matter for ETH conversions?

ETH values can have up to 18 decimal places. Standard JavaScript floating-point numbers only handle about 15 significant digits, so rounding errors appear for large Wei amounts. This tool uses BigInt and string arithmetic to remain exact.

How do I calculate a gas cost in ETH?

Multiply the gas limit by the gas price in Gwei, then convert that product from Gwei to ETH. For example: 21,000 gas × 20 Gwei = 420,000 Gwei = 0.00042 ETH.

Is 1 ETH exactly 10^18 Wei?

Yes. The Ethereum protocol defines 1 ETH = 1,000,000,000,000,000,000 Wei exactly. There are no approximations — all balances in the EVM are stored as Wei integers.

Gwei to ETH Converter

Instantly convert between Wei, Gwei, and ETH with full-precision arithmetic — no rounding errors.

Enter a Value

Type in any field to convert all denominations instantly.

Wei (10^-18 ETH)

Gwei (10^-9 ETH)

ETH (Ether)

Conversion Results

Wei

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Gwei

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ETH

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Quick Reference

Unit	Wei	Gwei	ETH
1 Wei	1	0.000000001	10^-18
1 Gwei	1,000,000,000	1	0.000000001
1 ETH	10¹⁸	1,000,000,000	1

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Summary

Ethereum uses three main denominations: Wei (the smallest unit, 1 ETH = 10^18 Wei), Gwei (10^9 Wei, used for gas prices), and ETH (the base currency). This tool converts between all three in real time using BigInt arithmetic so no precision is lost, even at extreme values like 1 Wei or 1,000,000,000 Gwei.

How it works

Enter a value in any of the three fields — Wei, Gwei, or ETH.
The tool detects which field you typed in.
BigInt arithmetic converts the value to all three denominations instantly.
Results update in real time as you type.
Click the copy icon next to any result to copy it to your clipboard.

Use cases

Convert gas prices from Gwei to ETH to estimate transaction costs.
Translate smart-contract amounts expressed in Wei to human-readable ETH.
Double-check RPC responses that return Wei values.
Calculate EIP-1559 base fee and priority fee totals in ETH.
Verify token transfer amounts during Ethereum development.
Understand wallet balances displayed in Wei by block explorers.
Quickly sanity-check gas estimates before signing a transaction.
Teach new developers about Ethereum denomination hierarchy.

Frequently Asked Questions

Last updated: 2026-10-05 · Reviewed by Nham Vu