Unit Converter
Convert between common units of length, weight, volume, temperature, and area. Metric and imperial both supported. Pick a category, choose your source and target units, enter your value, and read off the answer. Uses internationally-defined conversion factors.
Quick answer
Key ratios: 1 m = 3.281 ft. 1 kg = 2.205 lbs. 1 L = 0.264 US gallons. 1 mi = 1.609 km. °C = (°F − 32) × 5/9.
Unit Converter
How unit conversion works
Every non-temperature unit has a conversion factor to a base unit (meters for length, grams for weight, milliliters for volume, square meters for area). To convert A to B, you first multiply your input by A's factor to get the base unit, then divide by B's factor to get B. For example: 5 miles to kilometers: 5 × 1609.344 (to meters) ÷ 1000 (to km) = 8.047 km.
Temperature is special because the scales have different zero points. The calculator
converts to Celsius as an intermediate, then out to the target: Fahrenheit to Celsius is
(F − 32) × 5/9, and back out is C × 9/5 + 32. Kelvin is just
Celsius plus 273.15.
When to use it
Cooking recipes from a different country (UK cookbook calling for grams, US kitchen with measuring cups), travel math (kilometers on the speedometer, miles in your head), shipping calculations (lbs vs kg on customs forms), DIY measurements (inches to centimeters for an IKEA part list), and any time you encounter a unit you don't think in.
Common mistakes
- Confusing volume and weight for food. 1 cup of flour weighs ~120g, but 1 cup of sugar weighs ~200g. Volume-to-weight conversions depend on the substance's density.
- Using US cups in a UK recipe. US = 236.6 ml, UK = 284.1 ml, Australia = 250 ml. That's an 8–20% difference — enough to ruin baked goods.
- Temperature formulas inverted. C to F is
C × 9/5 + 32. F to C is(F − 32) × 5/9. Mixing them up gives wildly wrong answers. - Ignoring imperial vs US weight tons. A US ton is 2,000 lbs. An imperial ton (long ton) is 2,240 lbs. A metric ton (tonne) is 1,000 kg = 2,205 lbs.
Frequently asked questions
How do I convert between metric and imperial?
Use the calculator above. Key ratios: 1 m = 3.281 ft, 1 kg = 2.205 lbs, 1 L = 0.264 gallons, °C = (°F − 32) × 5/9.
What's the difference between fluid ounces and weight ounces?
Fluid ounces measure volume (~29.57 ml). Weight ounces measure mass (~28.35 grams). They're only equal for water.
How accurate are unit conversions?
The calculator uses standard conversion factors accurate to at least 6 significant figures — more than enough for any practical use.
Does a US cup equal a UK cup?
No. US = 236.6 ml, UK = 284.1 ml, Australia = 250 ml. This calculator uses US cups.