Convert between different units of measurement with precision
The CalcNest Unit Converter handles conversions across the most commonly needed measurement categories: length, weight and mass, temperature, volume, area, speed, and more. Whether you need to convert miles to kilometres, kilograms to pounds, Celsius to Fahrenheit, or litres to gallons, you get precise results instantly without needing to look up conversion factors or do manual arithmetic.
Conversions use the exact, internationally recognised conversion ratios defined by the International Bureau of Weights and Measures (BIPM) and the metric system. You can convert in both directions — metric to imperial, or imperial to metric — with a single click.
Metres, kilometres, centimetres, millimetres, miles, yards, feet, inches, nautical miles
Example: 1 mile = 1.60934 kilometres
Kilograms, grams, milligrams, pounds, ounces, stone, metric tonnes, short tons
Example: 1 kilogram = 2.20462 pounds
Celsius (°C), Fahrenheit (°F), Kelvin (K)
Example: 100°C = 212°F (water boiling point)
Litres, millilitres, cubic metres, gallons (UK & US), pints, fluid ounces, cups
Example: 1 litre = 1.75975 UK pints
Kilometres per hour, miles per hour, metres per second, knots
Example: 100 mph = 160.934 km/h
Square metres, square kilometres, square feet, square miles, acres, hectares
Example: 1 hectare = 2.47105 acres
The UK uses a mix of metric and imperial units in everyday life — distances on road signs are in miles, but food packaging uses grams and kilograms. The US primarily uses the imperial (customary) system. Scientific work globally uses the metric (SI) system. Here are the most useful conversions to know:
| Metric | Imperial / US | Exact Conversion |
|---|---|---|
| 1 kilometre | 0.621371 miles | ÷ 1.60934 |
| 1 kilogram | 2.20462 pounds | × 2.20462 |
| 1 litre | 1.75975 UK pints | × 1.75975 |
| 1 metre | 3.28084 feet | × 3.28084 |
| 0°C | 32°F | (°C × 9/5) + 32 |
| 100°C | 212°F | Water boiling point |
Multiply the Celsius temperature by 9, divide by 5, then add 32. Formula: °F = (°C × 9/5) + 32. For quick mental approximation, double the Celsius value and add 30 — this gives a rough but useful estimate.
UK and US gallons are different units. 1 UK (imperial) gallon = 4.54609 litres. 1 US gallon = 3.78541 litres. When a recipe or vehicle fuel economy refers to gallons, it matters significantly which type is meant — they differ by about 20%.
One stone = 14 pounds = approximately 6.35029 kilograms. The stone is used primarily in the UK and Ireland for body weight. To convert stone to kilograms: multiply by 6.35029.
Most metric-to-imperial conversions involve irrational or non-terminating decimal ratios because the two systems were developed independently. The metre was not defined in relation to the foot. Our converter uses the exact internationally defined conversion ratios for precision.
Yes, for most professional planning and engineering estimation purposes. The converter uses the exact BIPM-defined conversion factors. For legally precise measurements in regulated industries, always confirm with calibrated equipment and relevant standards.