Ethereum Unit Converter: Wei, Gwei, and Ether Explained

Why ether has subunits

Ethereum's native asset is divisible to 18 decimal places, and the EVM does all arithmetic in the smallest unit — wei — as unsigned 256-bit integers. Floating-point ether is a bug factory: 0.1 + 0.2 !== 0.3 in IEEE-754, and rounding at the 18th decimal loses real money at scale. The rule: store and compute in wei, format for humans only at the edges.

The unit ladder

Gas math you'll do weekly

Transaction cost = gas used × gas price (in gwei), paid in ether. A swap using 180,000 gas at 12 gwei costs 180,000 × 12 gwei = 2,160,000 gwei = 0.00216 ETH. Since EIP-1559, "gas price" splits into a base fee (burned) plus a priority tip; wallets quote maxFeePerGas and refund the difference.

Pitfalls that cost money

• JavaScript numbers top out at 2⁵³ — about 9 ETH in wei. Always use BigInt (1000000000000000000n) or a decimal library; Number("3 ETH in wei") silently loses precision.
• Decimals differ per token. ERC-20 tokens choose their own — USDC uses 6, most others 18. Reading balanceOf without dividing by the token's decimals gives answers 10¹²× off.
• Formatting: display with fixed decimals and explicit rounding — trailing-zero trimming can hide rounding that shortchanges users.

Convert wei/gwei/ether exactly, with BigInt precision, using the EVM Unit Converter — no floating-point traps.