Free Unit Converter — 7 Categories, 50+ Units
This unit converter handles the most common measurement categories: length, weight, temperature, volume, speed, area, and digital data. All conversions happen instantly in your browser — no server, no internet required after the page loads.
How to Use
- Select a category using the tabs at the top.
- Choose your From and To units from the dropdowns.
- Type a value — the result appears instantly.
- Click Swap to reverse the conversion and use the result as the new input.
- A quick reference table shows the value in all units of the selected category at once.
Supported Categories
- Length — km, m, cm, mm, mile, yard, foot, inch, nautical mile
- Weight — tonne, kg, g, mg, pound, ounce, stone
- Temperature — Celsius, Fahrenheit, Kelvin
- Volume — liter, mL, m³, US gallon, quart, pint, cup, fluid oz, tablespoon, teaspoon
- Speed — km/h, m/s, mph, knots, ft/s
- Area — km², m², cm², hectare, acre, sq mile, sq yard, sq foot, sq inch
- Data — bit, byte, KB, MB, GB, TB, KiB, MiB, GiB
Frequently Asked Questions
How is temperature conversion different from other units?
Most unit conversions are simple multiplication (e.g. 1 km = 1000 m). Temperature is different because the scales have different zero points. Converting Celsius to Fahrenheit requires both multiplication and addition: °F = (°C × 9/5) + 32. Kelvin starts at absolute zero, so K = °C + 273.15. This tool handles the offsets automatically.
What is the difference between KB and KiB?
A Kilobyte (KB) in the SI standard is 1,000 bytes. A Kibibyte (KiB) is 1,024 bytes (2¹⁰). The same distinction applies to MB/MiB and GB/GiB. Operating systems historically used 1,024-based units but called them KB/MB/GB, which caused confusion. Modern standards use KiB/MiB/GiB for powers of 2 and KB/MB/GB for powers of 10.
How accurate are the conversions?
Conversion factors are based on internationally defined exact values where available (e.g. 1 inch = 0.0254 m exactly, 1 pound = 0.45359237 kg exactly). Results are shown to up to 8 significant figures. For scientific applications requiring higher precision, use a dedicated scientific calculator.