8 Best Free Unit Converters Online (2026)
The best free unit converters online in 2026 — temperature, length, weight, speed, data storage, currency, number base, and CSV/JSON converters. Instant, no sign-up.
The 8 Best Free Unit Converters Online in 2026
Unit conversion is one of those everyday tasks that sounds simple but trips people up constantly. These free browser-based converters cover every common conversion scenario — from temperatures to file sizes to currency.
1. Universal Unit Converter — All Units in One Place
Convert between dozens of unit types — length, area, volume, mass, speed, pressure, energy, and more — all in a single interface. Covers both metric and imperial units for every scenario.
2. Temperature Converter — Celsius, Fahrenheit & Kelvin
Convert between Celsius, Fahrenheit, and Kelvin instantly. Includes a reference chart of common temperatures for cooking, weather, and science. The most searched converter on the web.
3. Length Converter — Imperial to Metric & Back
Convert between inches, feet, yards, miles, millimeters, centimeters, meters, and kilometers. Includes nautical miles and astronomical units for specialized needs.
4. Weight Converter — Pounds, Kilograms & More
Convert between ounces, pounds, stones, kilograms, grams, and metric tons. Essential for cooking with international recipes and understanding luggage weight limits.
5. Speed Converter — MPH, KPH & More
Convert between miles per hour, kilometers per hour, meters per second, knots, and Mach number. Useful for automotive, aviation, and sports performance tracking.
6. Data Storage Converter — Bytes to Gigabytes
Convert between bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Handles both SI (1000-based) and binary (1024-based) definitions — crucial for understanding storage specs.
7. Currency Converter — Live Exchange Rates
Convert between major world currencies with current exchange rates. Covers USD, EUR, GBP, JPY, CAD, AUD, and dozens more. Useful for travel planning and international commerce.
8. Number Base Converter — Decimal, Binary, Hex & Octal
Convert numbers between decimal, binary, octal, and hexadecimal number systems. Essential for programming, computer architecture courses, and color code conversion.
Featured Tools
Try these free tools directly in your browser — no sign-up required.
Unit Converter
Convert between hundreds of units across length, weight, temperature, speed, volume, and more. Fast, accurate, and works entirely in your browser.
Temperature Converter
Convert temperatures between Celsius, Fahrenheit, Kelvin, and Rankine instantly. Perfect for cooking, science, weather, and travel.
Length Converter
Convert length and distance between metres, kilometres, miles, feet, inches, yards, and more. Instant results for travel, construction, and science.
Weight Converter
Convert weight and mass between kilograms, pounds, ounces, grams, stone, tons, and more. Instant results for cooking, fitness, and shipping.
Speed Converter
Convert speed between miles per hour, kilometres per hour, metres per second, knots, Mach, and more. Great for travel, physics, and aviation.
Data Storage Converter
Convert digital storage units between bits, bytes, kilobytes, megabytes, gigabytes, terabytes, and petabytes. Uses both binary (1024) and decimal (1000) standards.
Currency Converter
Convert between 150+ world currencies using live exchange rates. Perfect for travel budgeting, international shopping, and finance.
Number Base Converter
Convert numbers between any bases from base 2 to base 36. Supports binary, octal, decimal, hexadecimal, and custom bases for advanced computing tasks.