Metric vs Imperial — Quick Reference Guide for Everyday Conversions
Whether you are reading a recipe from America, buying furniture from a European website, or checking the weather forecast in a different country, you will encounter both metric and imperial measurements. This quick reference gives you the conversions you need most often — plus links to our free converters for exact calculations.
The Two Systems at a Glance
📐 Metric (SI)
Used by 95% of the world. Base-10 system. Metres, kilograms, litres, Celsius. Simple to scale (multiply/divide by 10, 100, 1000).
📏 Imperial/US Customary
Used primarily in the US, Liberia, Myanmar. Feet, pounds, gallons, Fahrenheit. Irregular scaling (12 inches = 1 foot, 3 feet = 1 yard).
The metric system was formalised during the French Revolution and has since been adopted by virtually every country. The imperial system evolved from older English units and persists primarily in the United States for everyday use, though even American science and medicine use metric. This means cross-system conversion is a daily necessity for international communication.
Weight Conversions
| Metric | Imperial | Quick Rule |
|---|---|---|
| 1 kg | 2.205 lbs | Double and add 10% |
| 1 gram | 0.035 oz | 28g ≈ 1 oz |
| 1 tonne | 2,205 lbs | ≈ 1.1 US tons |
| 1 stone | 14 lbs / 6.35 kg | UK body weight unit |
The most common conversion people search for is kilograms to pounds — whether for luggage limits, body weight, or recipe scaling. Our Weight Converter handles all these instantly.
Length Conversions
| Metric | Imperial | Quick Rule |
|---|---|---|
| 1 cm | 0.394 inches | 2.54 cm = 1 inch |
| 1 metre | 3.281 feet | ≈ 3 ft 3 in |
| 1 km | 0.621 miles | Multiply km by 0.6 |
| 1 mile | 1.609 km | Multiply miles by 1.6 |
📚 Dig Deeper
Volume Conversions
| Metric | Imperial | Notes |
|---|---|---|
| 1 litre | 0.264 US gal | ≈ 4 cups |
| 1 ml | 0.034 fl oz | ≈ 1/5 teaspoon |
| 1 US gallon | 3.785 litres | UK gallon = 4.546 L |
| 1 US cup | 236.6 ml | ≈ 240 ml (rounded) |
Volume is where the two systems diverge most confusingly — a UK pint (568 ml) is larger than a US pint (473 ml), and recipes from different countries use different cup sizes. Our Volume Converter and Cooking Converter eliminate the guesswork.
Temperature Conversions
0°C
= 32°F (freezing)
37°C
= 98.6°F (body)
100°C
= 212°F (boiling)
The formula is °F = (°C × 9/5) + 32, but for quick mental estimates: double the Celsius value and add 30. That gives you a rough Fahrenheit within a few degrees. For exact results, use our Temperature Converter.
All 25 Converters in One Place
Beyond the everyday conversions listed above, our full converter directory includes specialist converters for pressure, energy, power, frequency, angle, data storage, fuel economy, precious metals, shoe sizes, clothing sizes, running pace, cycling speed, number bases, Roman numerals, and more. Each converter is free, instant, and works on any device without sign-up.
✓ Remember
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