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Unit Conversion

Unit Converter

Convert between common units of length, weight, volume, area, speed, and temperature.

How conversions work

For length, weight, volume, area, and speed, every unit is converted through a common base unit (meters, kilograms, liters, square meters, or meters/second) using a fixed multiplication factor, so any two units in the same category can be compared directly.

Temperature is different because Celsius, Fahrenheit, and Kelvin scales don't share a common zero point, so each conversion uses its own formula rather than a simple multiplier.

How to use this calculator

Pick a measurement type first (length, weight, volume, area, speed, or temperature), then choose the unit you're converting from and the unit you want. The result updates as you type — there's no separate submit step needed.

Metric vs. imperial

Metric units (meters, kilograms, liters) are the standard almost everywhere outside the US, and are also the base system used in science and engineering worldwide. Imperial and US customary units (miles, pounds, gallons, feet) remain standard for everyday use in the United States, and imperial units still appear in a few specific UK contexts (miles for road distances, for example, even though the UK otherwise uses metric).

Common conversions

  • 1 mile ≈ 1.60934 kilometers
  • 1 kilogram ≈ 2.20462 pounds
  • 1 US gallon ≈ 3.78541 liters
  • 0°C = 32°F = 273.15 K
  • 1 acre ≈ 43,560 square feet ≈ 4,047 square meters
  • 1 hectare ≈ 2.471 acres
  • 100 km/h ≈ 62.14 mph
  • 1 knot ≈ 1.151 mph (used for wind speed and marine/air navigation)

When you need a more specialised unit

This converter covers everyday length, weight, volume, area, speed and temperature. Recipes that call for teaspoons or cups, shoe and clothing sizes, very large astronomical distances, and engineering quantities such as acceleration, frequency, illuminance and viscosity each have their own converter — they are linked under Related calculators below.

Frequently asked questions

Why does temperature need a different method?

Celsius and Fahrenheit have different zero points and different-sized degrees, so converting between them requires both a multiplication and an offset (°F = °C × 9/5 + 32), not a simple factor like length or weight conversions use.

How precise are the results?

Results are shown to four decimal places using standard, widely published conversion factors, which is precise enough for everyday, cooking, travel, and classroom use.

Why do I need to pick a measurement type first?

Each type (length, weight, volume, area, speed, temperature) has its own set of units and conversion logic — selecting the type first narrows the From/To lists to units that are actually comparable, so you can't accidentally try to convert kilograms into liters.

Which conversion factors does this use — US or UK gallons and tons?

US customary units: the US liquid gallon (3.78541 L, not the larger UK imperial gallon) and the metric tonne (1,000 kg) for "tons." If you need UK/imperial gallon conversions specifically, the Fuel Economy Converter handles both US and UK gallons separately.

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