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Unit Converters

Convert length, weight, volume, area, temperature, speed, time, data sizes, energy, pressure and more, plus CSS units like px, rem and em.

Angle Converter Angle Converter: convert between degree, radian, gradian, arcminute and 3 more units instantly. Area Converter Area Converter: convert between square millimeter, square centimeter, square meter, hectare and 6 more units instantly. Astronomical Distance Converter Astronomical Distance Converter: convert between kilometer, mile, light-second, light-minute and 7 more units instantly. Data Size Converter (Bytes / Bits) Data Size Converter (Bytes / Bits): convert between bit, byte, kilobit, kilobyte (1000) and 11 more units instantly. Density Converter Density Converter: convert between kilogram per cubic meter, gram per cubic centimeter, gram per milliliter, gram per liter and 6 more units instantly. Electric Current Converter Electric Current Converter: convert between nanoampere, microampere, milliampere, ampere and 4 more units instantly. EM to PX Converter Convert em to pixels for CSS using a configurable root/base font size (default 16px). Energy Converter Energy Converter: convert between joule, kilojoule, megajoule, calorie and 8 more units instantly. Force Converter Force Converter: convert between newton, kilonewton, millinewton, dyne and 4 more units instantly. Frequency Converter Frequency Converter: convert between millihertz, hertz, kilohertz, megahertz and 4 more units instantly. Fuel Economy Converter Fuel Economy Converter: convert between kilometers per liter, liters per 100 km, miles per us gallon, miles per imperial gallon and 1 more units instantly. Inches to Pixels Converter Convert inches to pixels at any resolution: 96 DPI for screens, 300 DPI for print, or a custom value. Length Converter Length Converter: convert between nanometer, micrometer, millimeter, centimeter and 14 more units instantly. Mass Converter Convert SI mass units from microgram to tonne with significant-digit control, scientific notation and a table of every unit. Pixels to Inches Converter Convert pixels to inches at any resolution: 96 DPI for screens, 300 DPI for print, or a custom value. Power Converter Power Converter: convert between milliwatt, watt, kilowatt, megawatt and 5 more units instantly. Pressure Converter Pressure Converter: convert between pascal, hectopascal, kilopascal, megapascal and 7 more units instantly. PX to EM Converter Convert pixels to em for CSS using a configurable root/base font size (default 16px). PX to REM Converter Convert pixels to rem for CSS using a configurable root/base font size (default 16px). REM to PX Converter Convert rem to pixels for CSS using a configurable root/base font size (default 16px). Speed Converter Speed Converter: convert between meter per second, kilometer per hour, mile per hour, knot and 3 more units instantly. Temperature Converter Temperature Converter: convert between celsius, fahrenheit, kelvin, rankine and 1 more units instantly. Time Converter Time Converter: convert between nanosecond, microsecond, millisecond, second and 8 more units instantly. Volume Converter Volume Converter: convert between milliliter, centiliter, deciliter, liter and 15 more units instantly. Weight Converter Weight Converter: convert between microgram, milligram, gram, kilogram and 9 more units instantly.

Unit converters for everyday and technical work

Recipes in cups, room sizes in square feet, file sizes in mebibytes, CSS in rem: units get in the way constantly. These unit converters handle the common physical quantities as well as the units developers and designers use daily, with exact conversion factors and clear results.

Physical quantities

  • Distance and size – the length converter covers metric, imperial and nautical units; the area converter and volume converter handle square and cubic units, liters and US and imperial gallons.
  • Mass – the weight converter switches between kilograms, pounds, ounces and stones.
  • Temperature – the temperature converter handles Celsius, Fahrenheit and Kelvin, which need formulas rather than simple factors.
  • Motion and time – the speed converter and time converter.
  • Science and engineering – energy, power, pressure, force, density, frequency, angle, electric current, fuel economy and astronomical distances.

Units for developers and designers

  • Data sizes – the bytes converter distinguishes decimal units (1 KB = 1,000 bytes) from binary units (1 KiB = 1,024 bytes).
  • CSS units – px to rem, rem to px, px to em and em to px, based on the root or parent font size.
  • Print – inches to pixels and pixels to inches at the DPI you choose.

Common pitfalls

  • US vs imperial – a US gallon is about 3.785 liters, an imperial gallon about 4.546 liters; US and UK fluid ounces and pints differ too.
  • Weight vs mass – kilograms and pounds are units of mass; in everyday use "weight" means the same thing.
  • Storage sizes – a "500 GB" drive shows as about 465 GiB in operating systems that count in binary units.
  • Temperature differences – a change of 10 °C is a change of 18 °F, but 10 °C is 50 °F.
  • CSS rem – rem depends on the root font size, usually 16px, but users can change it for accessibility, which is exactly why rem is preferred for text.

Metric and imperial at a glance

Most of the world uses the metric system, while the United States uses customary units for everyday measures, and the UK mixes both (miles on road signs, liters at the pump). Science, medicine and engineering use SI units almost everywhere. When sharing measurements internationally, giving both values avoids misunderstandings.

Precision

Conversion factors are exact where definitions are exact (an inch is exactly 2.54 cm, a pound exactly 0.45359237 kg). Results are rounded for display; copy more decimals when you need them for engineering work. All conversions happen in your browser.

Frequently asked questions

Is a kilobyte 1,000 or 1,024 bytes?
Officially, a kilobyte (KB) is 1,000 bytes and a kibibyte (KiB) is 1,024 bytes. Many operating systems still label binary values with KB, MB and GB, which causes the apparent difference in disk sizes.
How do I convert Celsius to Fahrenheit?
Multiply by 9/5 and add 32. For example, 20 °C is 68 °F. The temperature converter also handles Kelvin.
How many pixels is 1rem?
By default 16 pixels, because browsers use a 16px root font size. If the root size changes, rem values scale with it.
Why are US and UK gallons different?
They come from different historical definitions. The US gallon is about 3.785 liters and the imperial gallon used in the UK is about 4.546 liters.