Number Conversion — Free & Private

Convert units and measurements, currencies and denominations, number bases and Roman numerals.

Runs 100% in your browser: your files and data never leave your device. No signup, no ads.

Tools in Number Conversion

Unit & Measurement Converter: Precision conversions across length, weight/mass, data storage, speed, and temp.
Currency & Denomination Calculator: Client-side currency conversion with reference rates, reverse calculation, and cash bill breakdown.
Base & Radix Converter: Convert Decimal, Hex, Binary, and Octal with BigInt precision and bit formatting.
Roman Numeral Converter: Convert between Arabic numbers (1-3999) and Roman numerals in either direction.
Number to Words & Currency Speller: Convert numbers, currency amounts, and decimals into written English and German words and ordinal phrases.