Unit Converter
Convert between 100+ units across 10 categories. Instant bidirectional conversion with a full reference table.
All Units Reference Table
| Unit | Value in Base Unit | Equivalent |
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How to Use the Unit Converter
- Pick a category using the chips above — Length, Weight, Temperature, Volume, Area, Speed, Time, Data, Pressure, or Energy.
- Enter a value in the left input field.
- Choose source and target units from the two dropdowns.
- Read the result instantly in the right field. You can also type in the right field for reverse conversion.
- Use the reference table below the converter to see all units relative to each other at once.
About Unit Conversion
Unit conversion is the process of expressing a measured quantity in a different unit of measurement without changing the underlying physical quantity. All conversions in this tool are based on exact or accepted SI (International System of Units) definitions. For example, one inch is defined as exactly 25.4 millimetres — this is not an approximation but a legal definition adopted by the US, UK, Canada, and Australia in 1959.
Length Conversions
Length is one of the seven SI base quantities. The metre (m) is the SI base unit. Common conversions include millimetres, centimetres, kilometres, inches, feet, yards, and miles. The metric system is used by most countries, while the imperial system (inches, feet, miles) remains common in the United States, UK for some purposes, and a few other countries. The nautical mile (1,852 m) is used in aviation and maritime navigation worldwide.
Weight and Mass
Mass and weight are technically different — mass is measured in kilograms, while weight is a force measured in newtons. However, in everyday usage, "weight" refers to mass. The kilogram (kg) is the SI base unit for mass. One pound is exactly 0.45359237 kilograms by definition. The metric tonne (1,000 kg) and the US short ton (2,000 lb ≈ 907.18 kg) are both commonly used in commerce and industry.
Temperature
Temperature conversion is special because it uses offset formulas, not simple multiplication. The three most common scales are Celsius (°C), Fahrenheit (°F), and Kelvin (K). Kelvin is the SI base unit and starts at absolute zero (−273.15 °C). Fahrenheit is used primarily in the United States for everyday temperatures. Celsius is the standard in most other countries. The Rankine and Delisle scales are less common but included for completeness.
Volume Conversions
The litre (L) is the most common volume unit in everyday use, though the SI-derived unit is the cubic metre (m³). One litre equals exactly 1,000 cubic centimetres. US and imperial volumes differ: a US gallon is 3.785 L while an imperial gallon is 4.546 L. This distinction matters for cooking, fuel consumption, and chemical mixing. US fluid ounces and UK fluid ounces are also slightly different values.
Speed, Time, and Data
Speed conversions are useful for travel planning (mph vs km/h), aviation (knots), and physics (m/s). Data size conversions are essential for developers and IT professionals comparing file sizes, storage capacities, and network transfer rates. This tool uses binary prefixes for data (1 KB = 1,024 bytes) which is standard in operating systems, though storage manufacturers often use SI prefixes (1 KB = 1,000 bytes).
Pressure and Energy
Pressure conversions between pascals, atmospheres, bar, psi, and mmHg are vital in engineering, meteorology, and medicine. Tyre pressure is often in psi or bar; blood pressure in mmHg; atmospheric pressure in hPa or mbar. Energy conversions between joules, calories, BTU, kilowatt-hours, and electron-volts span everyday cooking (calories), home electricity (kWh), and particle physics (eV). One kilowatt-hour equals exactly 3,600,000 joules.