Wei / Gwei / ETH Converter

Ethereum amounts look different depending on the layer you are working at. A gas price is quoted in Gwei. A smart contract emits events in Wei. A wallet shows balances in ETH. This converter ties all ten official denominations together — type a value in any unit and every other denomination updates instantly, with no floating-point rounding errors because all arithmetic runs on BigInt.

Load Sample starts with 21 Gwei — the baseline gas price for a simple ETH transfer — so the first thing you see is a realistic working number rather than a theoretical one. Pressing Load Sample again cycles through 1.5 ETH, 100 Gwei (high-congestion pricing), exactly 1 ETH expressed in Wei, and 0.001 ETH (one Finney).

The Controls and the Unit Scale

• Click any unit tab (Wei, Kwei, Mwei, Gwei, Szabo, Finney, ETH, KEther, MEther, GEther) to make that the input unit. The tab highlights in orange. Type your value and every other row converts immediately.
• Clicking a different unit tab while a result is displayed switches the input to that unit's converted value, so you can chain conversions without retyping.
• Each result card has its own Copy button. The value copies as a plain numeric string with no unit suffix, ready to paste into code, a transaction payload, or a spreadsheet.
• The input badge marks the unit you are editing so it is always clear which row is driving the calculation.

How It Calculates Without Rounding Errors

JavaScript's Number type loses precision beyond 15 to 16 significant digits, which means 1 ETH expressed as 1e18 Wei cannot safely round-trip through floating-point. This tool converts your input to a Wei integer using BigInt (shifting the decimal point), then divides back to the target denomination, preserving the exact fractional digits. The only loss of precision occurs if you type more decimal places than the source unit supports, for example sub-Wei fractions of a Gwei value, in which case those excess digits are silently truncated.

Accuracy Limits

• Values are exact for all standard Ethereum denominations down to 1 Wei. Sub-Wei fractions cannot be represented on the Ethereum network and are truncated at the input stage.
• Very large inputs above roughly 10 to the power 78 Wei will produce astronomically large numbers that are numerically correct but practically meaningless, as this figure exceeds the total ETH supply by many orders of magnitude.
• KEther, MEther, and GEther are official denominations in the Ethereum unit table but are rarely used in practice. They appear here for completeness. The three units used in almost every real context are Wei (contracts), Gwei (gas), and ETH (wallets).