Unit Converter
Convert length, weight, temperature, speed, area, volume, time, data, pressure and energy — instantly, in your browser.
Free Unit Converter — Length, Weight, Temperature, Speed & More
This free online unit converter handles 10 categories and over 80 units — length, weight and mass, temperature, speed, area, volume, time, data storage, pressure, and energy. Every conversion runs instantly in your browser with no upload, no signup, and no account required. Results update as you type and the full reference table shows all conversions for your input value at once.
The converter uses exact scientific conversion factors throughout. Temperature conversions use the correct offset formulas for Celsius, Fahrenheit, Kelvin, and Rankine — not approximations. Data storage covers both decimal (KB, MB, GB) and binary (KiB, MiB, GiB) units. The swap button lets you instantly reverse any conversion without re-entering values.
Supported Unit Categories
Length — millimeter, centimeter, meter, kilometer, inch, foot, yard, mile, nautical mile, micrometer, nanometer, light year.
Weight / Mass — milligram, gram, kilogram, metric ton, ounce, pound, stone, US ton, UK long ton.
Temperature — Celsius, Fahrenheit, Kelvin, Rankine — with full offset conversion formulas, not linear approximations.
Speed — meters per second, kilometers per hour, miles per hour, feet per second, knots, Mach.
Area — square meters, square feet, square inches, acres, hectares, square miles, square kilometers.
Volume — liters, milliliters, cubic meters, gallons (US and UK), pints, quarts, cups, fluid ounces, cubic feet.
Time — nanoseconds through years, including weeks, months, and average year length.
Data Storage — bits, bytes, kilobytes through terabytes, and binary kibibyte, mebibyte, gibibyte.
Pressure — pascal, kilopascal, bar, atmosphere, PSI, mmHg.
Energy — joules, kilojoules, calories, kilocalories, watt-hours, kilowatt-hours, BTU, electronvolt.
Who Uses a Unit Converter?
Students converting between metric and imperial units for physics or chemistry homework. Engineers checking pressure or energy unit equivalents across specifications written in different systems. Cooks converting cups to milliliters or grams for international recipes. Travellers converting miles to kilometers or Fahrenheit to Celsius. Developers calculating data storage sizes between bytes, kilobytes, and kibibytes. Athletes tracking speed in different units across GPS devices and training plans.
Need to analyze or format text alongside your calculations? The Word Counter & Text Analyzer runs the same way — instant, private, no upload. Working with JSON data from an API? Try the JSON Formatter.
Frequently Asked Questions
How accurate are the conversions?
All conversions use exact or widely-accepted scientific factors. Temperature uses precise offset formulas. For most practical purposes the results are accurate to at least 6 significant figures. Very large or very small values are displayed in scientific notation to avoid precision loss.
Why is temperature conversion different from other units?
Most unit conversions are simple multiplications. Temperature scales have different zero points, so they require an offset formula. For example, 0°C is 32°F — not 0°F. This converter handles Celsius, Fahrenheit, Kelvin, and Rankine correctly using the full formula, not a linear approximation.
What is the difference between KB and KiB?
KB (kilobyte) is 1,000 bytes in the decimal system used by storage manufacturers and network providers. KiB (kibibyte) is 1,024 bytes in the binary system used by operating systems. This converter includes both so you can switch between them accurately.
Can I convert multiple values at once?
The reference table below the main converter shows your input value converted to all units in the selected category simultaneously — so you can see every equivalent in one view without changing the dropdowns.
Is my data uploaded to a server?
No. All conversions run locally in your browser using JavaScript. Nothing is sent to any server — there is nothing to upload.
How do I convert in the opposite direction?
Click the swap button (⇄) between the two dropdowns. It reverses the from and to units and carries the result back as the new input — so you can go back and forth without retyping.