Convert any unit instantly — length, weight, temperature, speed, volume, data & more.
Select a category and enter a value.
CalcHub's unit converter is the most comprehensive free conversion tool available online. Covering 10 measurement categories and over 80 individual units, it handles everything from everyday conversions like kilometers to miles and kilograms to pounds, to specialized conversions like data storage units and angular measurements. All conversions happen instantly in your browser — no page reload, no waiting, and no ads.
Whether you're a student working through physics problems, a traveler converting currencies and distances, a cook adapting a recipe from cups to milliliters, a developer thinking about file sizes, or an engineer working across metric and imperial systems, our converter has you covered. Simply select your category, choose your source and target units, enter a value, and see results across every unit in that category simultaneously.
The length converter covers millimeters, centimeters, meters, and kilometers in the metric system, plus inches, feet, yards, and miles in the imperial system. Nautical miles and light-years are also available for specialized use. The metric system, used by 95% of the world, is based on powers of 10 making unit conversions straightforward. The US customary system uses historical ratios (12 inches = 1 foot, 3 feet = 1 yard, 1,760 yards = 1 mile) that require more calculation — exactly what our converter handles automatically.
Weight conversions include milligrams, grams, kilograms, and metric tonnes alongside ounces, pounds, and US/UK tons. The distinction between weight (a force) and mass (a quantity of matter) matters in physics, but for everyday purposes our converter handles both. Conversion factors are exact: 1 kilogram = 2.20462 pounds, 1 pound = 453.592 grams, 1 ounce = 28.3495 grams.
Temperature conversion is unique because it's not a simple multiplication — it requires both multiplication and addition/subtraction due to different zero points. Celsius to Fahrenheit: °F = (°C × 9/5) + 32. Fahrenheit to Celsius: °C = (°F − 32) × 5/9. Kelvin (the SI base unit for thermodynamic temperature) starts at absolute zero: K = °C + 273.15. Our converter handles all three directions automatically.
In the digital age, understanding data sizes is essential. Bits (b) are the smallest unit; bytes (B) contain 8 bits. Beyond bytes: 1 Kilobyte = 1,024 bytes, 1 Megabyte = 1,024 KB, 1 Gigabyte = 1,024 MB, 1 Terabyte = 1,024 GB. Note that storage manufacturers often use base-10 definitions (1 GB = 1,000,000,000 bytes) while operating systems use base-2 (1 GB = 1,073,741,824 bytes) — our converter uses the standard binary definitions.