Unit converter: how it works
Every unit in a category is defined as a multiple of one base unit: metres for length, kilograms for mass, litres for volume. To convert, the value is first multiplied into the base unit and then divided by the target unit's factor. For example, to go from miles to kilometres the tool uses 1 mile = 1,609.344 m and 1 km = 1,000 m.
Temperature is the exception because the scales do not share a zero. Celsius, Fahrenheit and Kelvin are converted with their own formulas. The converter handles length, weight, volume, area, speed, digital storage, time and temperature, and it runs entirely in your browser.
Formula and assumptions
Formula
Value × (from-unit factor ÷ to-unit factor); temperature uses its own formulas.
Assumptions
- US customary volumes (cup, gallon, etc.) are used for volume units.
- Digital storage uses 1024-based units.
Worked example
Three typical conversions
- 5 miles to kilometres: 5 × 1,609.344 ÷ 1,000 = 8.04672 km.
- 72 °F to Celsius: (72 − 32) × 5 ÷ 9 = 22.22 °C.
- 1 kilogram to pounds: 1 ÷ 0.45359237 = 2.2046 lb.
Result: 8.04672 km, 22.22 °C and 2.2046 lb.
Limitations
- Volume uses US customary units (cup, gallon, fluid ounce). A UK (imperial) gallon is about 4.546 litres, whereas the US gallon used here is 3.785 litres.
- Digital storage uses 1,024-based units (1 KB = 1,024 bytes), the way many operating systems report it. Storage makers often use 1,000, so a "500 GB" drive can show as less.
- A year is taken as 365 days, with no leap years or calendar rules.
- Results are shown rounded; for scientific or legal use, check the exact definitions.
