Convert between common units
💡 Why Convert Units? Whether you are following a recipe, building IKEA furniture, or calculating how far that rental car will take you — unit conversions make the world smaller and math easier. This tool handles length, weight, temperature, and more!
An inch was once defined as the length of three barleycorns laid end to end — it wasn't standardized to exactly 2.54 centimeters until an international agreement in 1959.
As an Amazon Associate we earn from qualifying purchases.
We do our best to link products that we genuinely believe are organic, no disposable junk, sustainable, and built to last.
A unit converter is a tool that translates measurements from one unit system to another. Whether you need to convert kilometers to miles for a road trip, kilograms to pounds for a recipe, or Celsius to Fahrenheit for travel—our converter handles it all instantly.
Length conversion covers metric (meter, kilometer, centimeter, millimeter) and imperial (mile, yard, foot, inch) systems. The relationship between systems is standardized internationally—1 inch equals exactly 2.54 centimeters. Weight conversion includes metric (kilogram, gram, milligram) and imperial (pound, ounce, stone) units. Kitchen recipes often require converting between grams and cups, making these conversions essential for cooking.
Temperature conversion uses different zero-points and scales. Celsius freezes at 0° and boils at 100°. Fahrenheit freezes at 32° and boils at 212°. Kelvin starts at absolute zero (-273.15°C), used in scientific applications.
Our converter displays results with 6 significant figures for accuracy. For everyday use, you can round to reasonable precision—converting a recipe might need grams, while converting distance for driving might need only miles.
Example: Say you convert 100 Fahrenheit to Celsius. First to base Celsius: (100 − 32) × 5/9 = 37.78. Since the target is already Celsius, the result is 37.78°C — roughly human body temperature.
Length, weight, and most other units share a common zero point, so converting between them is a simple multiplication. Temperature scales have different zero points (0°C vs 32°F vs 0K), so converting requires shifting the scale, not just multiplying by a ratio.
The converter displays 6 significant figures for precision, which matters for scientific or technical use. For everyday purposes like cooking or driving directions, you can safely round the result to whatever precision is practical.
Most are internationally standardized exact values — for example, 1 inch equals exactly 2.54 centimeters. A few, like acres to square meters, use widely accepted precise approximations that are accurate to many decimal places.