Metric vs Imperial Units

A practical guide to converting between metric and imperial length, weight, volume, and temperature units.

The metric system is decimal-based (meters, grams, liters) and used by most countries. The US customary (imperial-related) system still dominates everyday US length, weight, and volume measures.

Handy length facts

• 1 inch = 2.54 cm exactly
• 1 foot = 30.48 cm
• 1 mile ≈ 1.609 km

Weight and volume

• 1 kilogram ≈ 2.205 pounds
• 1 pound ≈ 0.454 kg
• 1 US fluid ounce ≈ 29.57 ml

Temperature

Celsius and Fahrenheit are not scaled by a simple multiply alone. Water freezes at 0°C / 32°F and boils at 100°C / 212°F. Use °F = (°C × 9/5) + 32.

Convert common values

Browse pre-filled pages in the conversion hub or open the unit converter.