Quick converter
Free Online Unit Converters
Accurate conversions for length, mass, temperature, area, volume, time, speed, pressure, energy, power and digital storage — with the formula and a worked example on every page.
Converter categories
Length Converters
- Inches to centimeters
- Centimeters to inches
- Feet to meters
- Meters to feet
- Miles to kilometers
- Kilometers to miles
- Nautical miles to kilometers
- Millimeters to inches
Mass Converters
- Kilograms to pounds
- Pounds to kilograms
- Grams to ounces
- Ounces to grams
- Kilograms to stone
- Stone to kilograms
- Metric tonnes to kilograms
- Kilograms to grams
Temperature Converters
- Degrees Celsius to degrees Fahrenheit
- Degrees Fahrenheit to degrees Celsius
- Degrees Celsius to kelvins
- Kelvins to degrees Celsius
- Degrees Fahrenheit to kelvins
- Kelvins to degrees Fahrenheit
Area Converters
- Square meters to square feet
- Square feet to square meters
- Acres to hectares
- Hectares to acres
- Square kilometers to square miles
- Square miles to square kilometers
- Square inches to square centimeters
- Square centimeters to square inches
Volume Converters
- Liters to US liquid gallons
- US liquid gallons to liters
- Milliliters to US fluid ounces
- US fluid ounces to milliliters
- US customary cups to milliliters
- Milliliters to liters
- US liquid quarts to liters
- US liquid gallons to Imperial gallons
- View all 30 →
Time Converters
Speed Converters
- Kilometers per hour to miles per hour
- Miles per hour to kilometers per hour
- Meters per second to kilometers per hour
- Kilometers per hour to meters per second
- Knots to kilometers per hour
- Knots to miles per hour
- Miles per hour to feet per second
Pressure Converters
- Pounds-force per square inch to bars
- Bars to pounds-force per square inch
- Pounds-force per square inch to kilopascals
- Kilopascals to pounds-force per square inch
- Millimeters of mercury to kilopascals
- Kilopascals to millimeters of mercury
- Standard atmospheres to pascals
- Standard atmospheres to pounds-force per square inch
Energy Converters
- Kilowatt-hours to kilojoules
- Kilojoules to kilowatt-hours
- Kilocalories to kilojoules
- Kilojoules to kilocalories
- BTUs to joules
- Joules to calories
- Watt-hours to joules
Power Converters
- Kilowatts to mechanical horsepower
- Mechanical horsepower to kilowatts
- Watts to kilowatts
- Kilowatts to watts
- BTU per hour to watts
- Watts to BTU per hour
- Megawatts to kilowatts
Digital Information Converters
- Gigabytes to megabytes
- Megabytes to gigabytes
- Terabytes to gigabytes
- Gigabytes to terabytes
- Gigabytes to gibibytes
- Gibibytes to gigabytes
- Bytes to bits
- Megabytes to kilobytes
Why Convertly
Exact definitions
Every unit comes from one registry that records its definition, so the same unit never has two values on different pages.
Shown working
Each converter shows its formula and a worked example, and lists the assumptions that apply, such as US versus Imperial gallons.
Fast and private
Pages are lightweight, calculations run in your browser, and nothing you type is sent to a server.
Need a calculator instead of a converter? Try the general conversion calculator.