Unit Converter

Convert between hundreds of units across length, weight, temperature, area, volume, speed, and data storage.

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About This Unit Converter

This tool converts between units across seven measurement categories: Length, Weight, Temperature, Area, Volume, Speed, and Data. Select a category, enter your value, choose the source and target units, and the conversion result appears instantly. The swap button reverses the conversion direction without re-entering values.

The Two Global Unit Systems

The world uses two primary measurement systems: the metric system (International System of Units, SI) — used by virtually every country — and the imperial/US customary system, used primarily in the United States. Metric is decimal-based (all conversions are powers of 10), making arithmetic between units simple. Imperial units have arbitrary historical ratios (12 inches to a foot, 3 feet to a yard, 1,760 yards to a mile), requiring memorisation.

Temperature Conversion Rules

Temperature is the only category where conversion is not a simple multiplication. Celsius to Fahrenheit: °F = (°C × 9/5) + 32. Fahrenheit to Celsius: °C = (°F − 32) × 5/9. Celsius to Kelvin: add 273.15. Key reference points: 0°C = 32°F (water freezes), 37°C = 98.6°F (normal body temperature), 100°C = 212°F (water boils).

Data Storage Units

Data units use two different base conventions that cause frequent confusion. The SI standard defines 1 Kilobyte = 1,000 bytes (used by hard drive manufacturers and internet speeds). The binary standard defines 1 Kibibyte = 1,024 bytes (used historically by operating systems). This is why a 1 TB hard drive shows as ~931 GB in Windows — the drive uses SI, the OS uses binary. This tool uses the SI standard (powers of 1,000) matching modern usage.

Practical Quick Conversions

  • Kilometres to miles: multiply by 0.621 (or multiply by 6 and drop the last digit for a quick estimate)
  • Kilograms to pounds: multiply by 2.205
  • Litres to gallons (US): multiply by 0.264
  • Celsius to Fahrenheit quick estimate: double the Celsius value and add 30