The Quick Guide to Metric and Imperial Conversions
2026-06-03 · 5 min read
A handful of conversion factors cover most daily needs. Here they are — plus the one conversion you cannot do with a simple multiply.
Most of the world uses metric; a few countries still use imperial; and everyone occasionally needs to convert between them. A small set of factors covers the vast majority of everyday cases.
Length
- 1 inch = 2.54 cm (so cm ÷ 2.54 = inches)
- 1 foot = 30.48 cm
- 1 mile = 1.609 km
Weight
- 1 kg = 2.205 lb
- 1 pound = 0.4536 kg
- 1 ounce = 28.35 g
Temperature is the odd one out
Length and weight conversions are just multiplication. Temperature is not, because the scales have different zero points. To convert Celsius to Fahrenheit: F = C × 9/5 + 32. The "+ 32" is why you cannot just multiply.
A fast mental estimate: double the Celsius value and add 30. 20°C ≈ 70°F (actual: 68°F). Close enough for weather.
Convert anything
The Unit Converter handles length, weight, temperature, area, volume, and speed with precise factors, so you never have to remember them.