Unit Converter
Convert length, weight, temperature, volume, area, and speed units instantly.
Conversions are computed locally in your browser.
What is Unit Converter?
Unit Converter switches between length, weight, temperature, volume, area, and speed units instantly — cm to inches, kg to pounds, Celsius to Fahrenheit, and more. Pick a category, choose your units, and type in either field; the other updates live.
Key features
- Six categories: length, weight, temperature, volume, area, speed
- Type in either field — both stay in sync
- Swap units with one click
- Handles temperature correctly (not a simple ratio like the others)
How to convert between units correctly
The Unit Converter switches between common measurement units instantly, entirely in your browser.
Steps
- Pick a category — length, weight, temperature, volume, area, or speed.
- Choose your units in the "from" and "to" dropdowns.
- Type a value. Either field accepts input; the other updates live. Use the swap button to flip direction.
Why temperature is handled differently
Every other category here converts by a simple multiplication (1 inch is always exactly 2.54 cm, no matter the value). Temperature doesn't work that way — Celsius, Fahrenheit, and Kelvin each start counting from a different zero point, so converting between them requires shifting by an offset, not just scaling. That's why 0°C becomes 32°F (not 0°F), and why a naive "just multiply" approach — which works fine for length or weight — gives the wrong answer for temperature.
A note on precision
Conversion factors here use the internationally defined exact values (for example, 1 inch = 2.54 cm exactly, 1 pound = 0.45359237 kg exactly) rather than rounded approximations, so results stay accurate even for large numbers.
Spellkit's Unit Converter runs entirely in your browser — nothing you type is sent anywhere.
Privacy
Every conversion is local arithmetic in your browser; the numbers you enter are never sent to a server.