Unit Converter

Convert units, calculate fees

Exact base-integer conversion across the wei family (wei to ether, the way Ethereum actually counts) and the satoshi family (msat to BTC, Lightning-scale included) — plus the fee math every bitcoiner does daily: transaction size in vB times fee rate in sat/vB. No exchange rates are fetched, because a converter that needs a price API stops working the moment you go offline. This one never does.

How the Unit Converter works

Unit mistakes in crypto are expensive in a way decimal mistakes elsewhere are not, because the smallest units are enormous: one ether is 10¹⁸ wei, one bitcoin is 10⁸ satoshi, and one satoshi is itself 10³ millisatoshi in Lightning's accounting. Floating-point arithmetic silently loses precision at exactly these magnitudes — so this converter does all arithmetic in JavaScript BigInt, the base integer units themselves, and only formats to decimal strings at the end. Converting 12,345,678,901,234,567,890 wei is exact, not approximate.

The two families are deliberately kept apart. Wei→ether is a fixed 18-decimal relationship, and msat→BTC a fixed 11-decimal one; but wei→BTC or sat→ETH requires a market price, and prices require a data feed. The moment a converter fetches a price, it stops working offline, starts making network requests tied to your queries, and bakes a stale rate into your math. This tool refuses that trade: it converts units, not value, and says so.

The fee calculator covers the multiplication every bitcoiner does before confirming a send: transaction weight in virtual bytes (vB) times the fee rate in sat/vB, both numbers your wallet shows you. 141 vB at 12 sat/vB is 1,692 satoshi — computed exactly, then also expressed in BTC so you can sanity-check against the amount you are sending. If a fee ever looks wrong relative to the transfer, that is your signal to stop and decode the transaction first.

Unit Converter — questions