Unit Converter
Convert between units of length, weight, temperature, area, volume and speed instantly. All conversions happen in your browser — no data uploaded. Perfect for everyday metric to imperial conversions and scientific calculations.
How to Use the Unit Converter
Select a category tab (Length, Weight, Temperature, Area, Volume or Speed). Enter the value you want to convert in the input field, then choose your source unit from the left dropdown and your target unit from the right dropdown. The result updates automatically as you type. Click the ⇄ swap button to reverse the conversion direction instantly.
Metric vs Imperial Systems
The metric system (SI) is used by most of the world and is built on base units of 10 — metres for length, kilograms for mass, litres for volume. The imperial system is primarily used in the United States (and partially in the UK) and uses units like inches, pounds and gallons. Converting between the two requires fixed multiplication factors, which this tool handles automatically.
- 1 inch = 2.54 cm exactly
- 1 mile = 1.609344 km exactly
- 1 pound = 0.45359237 kg exactly
- 1 US gallon = 3.785411784 litres
Common Conversion Reference
| From | To | Multiply by |
|---|---|---|
| km | miles | 0.621371 |
| miles | km | 1.609344 |
| kg | lb | 2.20462 |
| lb | kg | 0.453592 |
| metres | feet | 3.28084 |
| litres | US gallons | 0.264172 |
| km/h | mph | 0.621371 |
| knots | km/h | 1.852 |
Temperature Conversion Formulas
Temperature cannot be converted with a simple multiplication factor — it requires offset formulas:
- Celsius to Fahrenheit: °F = (°C × 9/5) + 32
- Fahrenheit to Celsius: °C = (°F − 32) × 5/9
- Celsius to Kelvin: K = °C + 273.15
- Kelvin to Celsius: °C = K − 273.15
- Fahrenheit to Kelvin: K = (°F − 32) × 5/9 + 273.15
Key reference points: Water freezes at 0°C / 32°F / 273.15 K and boils at 100°C / 212°F / 373.15 K. Absolute zero is 0 K / −273.15°C / −459.67°F.
Frequently Asked Questions
How do I convert km to miles?
Multiply kilometres by 0.621371 to get miles. For example, 100 km = 62.14 miles. Use the Length tab, select km as source and mile as target, then type 100.
What is the formula for Celsius to Fahrenheit?
Use °F = (°C × 9/5) + 32. So 20°C = (20 × 1.8) + 32 = 36 + 32 = 68°F. For the reverse, use °C = (°F − 32) × 5/9.
How many pounds are in a kilogram?
There are approximately 2.20462 pounds in one kilogram. Conversely, one pound equals 0.453592 kg. So 70 kg ≈ 154.3 lbs.
What is a nautical mile?
A nautical mile is exactly 1,852 metres (about 1.1508 statute miles). It is defined as one minute of arc along a meridian of the Earth and is used in aviation and maritime navigation.