Unit Converter
Convert between length, mass, volume, area, speed, time and temperature.
Overview
The Unit Converter switches values between common measurement systems for length, mass, volume, area, speed, time and temperature. Choose a category, type your value and unit, and read off the equivalents in metric and imperial — no scrolling through 17 menus.
It is built for travellers reading foreign signage, recipe-readers translating ounces to grams, engineers cross-checking spec sheets and students doing conversion homework. Mixing up mi and km or lb and kg is a classic error this tool fixes.
How it works
Most conversions are simple linear scaling: 1 inch = 25.4 mm, 1 mile = 1.609 km, 1 lb = 0.45359 kg and so on. Internally each unit has a factor that converts it to a category base unit (metre, kilogram, second, m², m³, m/s), and conversion between any two is value * factor_from / factor_to.
Temperature is the exception — Celsius, Fahrenheit and Kelvin have different zero points. Conversion uses an affine formula: F = 9/5 * C + 32, K = C + 273.15, with inverses straightforward. The converter handles every standard pair correctly.
Examples
100 km/h → 62.137 mph
500 g → 17.637 oz
72°F → 22.22°C
1 acre → 4046.86 m²
FAQ
Is conversion lossless?
For exact conversion factors (defined by international standards), yes. Floating-point can introduce tiny rounding noise.
Why is temperature different?
Temperature scales have different zero points and different degree sizes, so converting requires both a multiplier and an offset. Other units only need a multiplier.
What's the difference between US and Imperial units?
The US gallon (3.785 L) is smaller than the imperial gallon (4.546 L). US fluid ounces and imperial ounces also differ slightly. The converter labels each explicitly.
Are units always positive?
Length, mass, area and volume must be. Temperature can be negative (or even below absolute zero in nonsense input, which the converter flags).
Can I add custom units?
This tool focuses on the common categories. For specialist domains (astronomical, nuclear, financial), dedicated converters do a better job.