How Unit Conversion Works
All unit converters use a technique called base-unit normalisation. Every unit is stored as a ratio relative to one base unit per category. To convert, multiply by the source ratio then divide by the target ratio.
Converted = InputValue × (SourceFactor ÷ TargetFactor)
Length base = 1 metre
1 km → factor 1000
1 cm → factor 0.01
1 inch → factor 0.0254
1 mile → factor 1609.344
Temperature Is Special
Temperature uses an offset formula because the zero points of Celsius and Fahrenheit are not the same:
°F = (°C × 9/5) + 32
°C = (°F − 32) × 5/9
K = °C + 273.15
Common Conversions Cheat Sheet
- 1 mile = 1.609 km
- 1 kg = 2.205 lbs
- 1 gallon (US) = 3.785 litres
- 1 inch = 2.54 cm
- 0°C = 32°F = 273.15 K
- 100°C = 212°F (boiling point of water)
Why Do Countries Use Different Systems?
The metric system (SI) was standardised in 1875 and adopted by most of the world. The imperial system persists in the USA, UK (partially), and Myanmar. The metric system is base-10, making calculations far simpler — 1 km = 1,000 m, not 5,280 feet.
Convert between 50+ units across 8 categories — length, weight, temperature, speed, and more.
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