Converting between units is one of the most common everyday maths tasks. Whether you are following a recipe, checking your weight, or reading a weather forecast, quick conversions save time and prevent mistakes. Use our all-in-one Unit Converter to evaluate conversions across length, weight, temperature, area, volume, and data storage directly in your browser.
Length conversions
Most of the world uses the metric system (metres, kilometres, centimetres). The US, UK, and a few other countries also use imperial units (feet, inches, miles).
| From | To | Multiply by |
|---|---|---|
| Metres | Feet | 3.28084 |
| Feet | Metres | 0.3048 |
| Kilometres | Miles | 0.621371 |
| Miles | Kilometres | 1.60934 |
| Inches | Centimetres | 2.54 |
| Centimetres | Inches | 0.393701 |
Quick approximation: To convert metres to feet, multiply by 3.3. To convert km to miles, multiply by 0.6. Use the length converter for exact results.
Weight conversions
| From | To | Multiply by |
|---|---|---|
| Kilograms | Pounds | 2.20462 |
| Pounds | Kilograms | 0.453592 |
| Ounces | Grams | 28.3495 |
| Stones | Kilograms | 6.35029 |
A stone (14 pounds) is commonly used for body weight in the UK. Use the weight converter for any conversion. The BMI guide shows how weight converts to health metrics.
Temperature conversions
The three common scales have different zero points and different step sizes:
| Scale | Freezing point | Boiling point |
|---|---|---|
| Celsius | 0°C | 100°C |
| Fahrenheit | 32°F | 212°F |
| Kelvin | 273.15 K | 373.15 K |
Key formulas:
- °F = °C × 9/5 + 32
- °C = (°F − 32) × 5/9
- K = °C + 273.15
Quick approximation: Double the Celsius and add 30 to get Fahrenheit. 20°C ≈ 2×20 + 30 = 70°F (exact: 68°F). Use the temperature converter for precise values.
At −40 degrees, both Celsius and Fahrenheit read the same: −40°C = −40°F. The degrees vs radians guide covers angle measurement for trigonometry.
Frequently asked questions
How many feet are in a metre? There are approximately 3.28084 feet in one metre.
How many centimetres are in an inch? There are exactly 2.54 centimetres in one inch.
Which is longer, a kilometre or a mile? A kilometre (1000 m) is shorter than a mile (1609.344 m). One mile equals approximately 1.609 kilometres.
What is absolute zero? Absolute zero is the lowest possible temperature: 0 K, −273.15°C, or −459.67°F. At this point, all molecular motion theoretically stops.