Measurement conversion charts and converters for metric, imperial and US customary systems. Includes from everyday use to scientific calculators, thousands of units, definitions, abbreviations and formulas.
Please choose a unit conversion category from the list below.
Metric and imperial weight conversions for pound, kilogram, gram, ounce, carat, ton, stone and many more.
Access several weight conversion tables.
Convert many metric and imperial length units such as meter, centimeter, inch, foot, yard, kilometer, mile, ...
Includes several popular printable conversion charts.
Metric and imperial volume conversions for liter, gallon, cup, quart, ounce, cubic meter, cubic feet and many more.
Access the most popular volume charts.
Metric and imperial area units, acre, hectare, square meter, square feet, ...
Includes several conversion tables.
Convert many pressure units, bar, pascal, kpa, psi, atm, torr (mmHg), ...
Access the most common pressure tables.
Celsius, fahrenheit, kelvin, reaumur and rankine.
Includes charts, formulas and definitions.
Cooking recipe units, teaspoons, tablespoon, dessertspoons, cups, quarts, gallons and many more.
Men's and women's clothing, shoes and ring size conversions.
Foot/square second, kilometer/hour second, meter/square second, mile/hour minute, ...
Base number conversions from base 2 to base 36, including binary, octal, decimal, hex and many more.
Calorific units, btu/cubic foot, joule/cubic meter, therm/cubic foot, ...
Convert circular and angle units such as radian, degree, grade, minute, second, circumference, sextant, octant, ...
Currency conversions for all countries, updated daily.
Data transfer units, adsl, modem, usb, ethernet, fiber optics and other several networking devices.
Convert time, second, millisecond, minute, hour, day, week, month, year, century, ...
Gram/cubic millimeter, kilogram/liter, ounce/cubic foot, pound/gallon, ...
Digital storage units, bit, byte, megabyte, gigabyte, terabyte, exabyte, ...
Takes you to a page where you'll find so many electrical conversions such as resistance, capacitance, conductance, current, charge, conductivity, electric field, ...
Energy and work units, btu, calorie, joule, kilojoule, newton meter, kilowatt hour and many more....
Includes several charts.
Flow mass, flow volume and molar units.
Gram per second, pound per second, cubic meter per second, gallon per hour, kilomole per hour, ...
Convert force units, dyne, gram force, kilogram force, kilonewton, newton, ounce and pound force, ...
Hertz, kilohertz, radian hour, degree second, revolution minute, ...
Fuel economy conversions within and between the North American and European metrics.
Miles per gallon (mpg), liters per 100 kilometers, and many more.
Heat transfer coefficient, heat capacity and flux density units.
Calorie per second square centimeter, calorie/gram celsius, joule/second square foot, ...
Illumination, luminance, luminous intensity units.
Lux, flame, phot, nox, lumen/square meter, meter-candle, nit, lambert, candela (candle), ...
Magnetic flux and flux density units.
Maxwell, weber, tesla per square meter, tesla, gauss, weber per square meter, maxwell per square inch, ...
Power units, btu/hour, megawatt, gigawatt, horsepower, joule/hour and many more.
Convert radioactivity, radiation exposure, absorbed dose units.
Curie, becquerel, roentgen, rem, sievert, gray, rad, ...
Convert sound units, bel, decibel (dB) and neper (Np).
Metric and imperial speed conversion, meter per second, foot per minute, kilometers per hour, miles per hour, inch per second, ...
Conversions for rotational force units, kilogram force meter, newton meter, ounce force inch, pound force foot, ...
Dynamic and kinematic viscosity conversions.
Poise, centipoise, pascal second, newton per square meter, square meter/second, square foot/second, ...
History of Measurement Systems
People have been measuring things for thousands of years.Ancient egyptians used fingers, hands and arms to measure things.
One finger is a digit, 4 fingers a palm, distance between their elbow to the fingers is a cubit etc. All these units of measurement were based on something familiar to them such as their body parts but even the results varied from person to
person. Almost all countries or cultures used different units of measurement and conversion of units within or between the same systems have become a problem. There was no agreed upon standard of measurement.
Imperial system is derived from the old English units which evolved from the hundreds of Roman, Celtic and Anglo-Saxon
units used in the history. English units have been used until 1824 and then the official imperial system was defined by the British Weights and Measures Act as the standard measurement system in Britain and in commonwealth countries. Within
years, the units were refined and reduced. In 1965, the metric system was adopted but still several common units are being
used in everyday life (foot, inch, mile etc).
US Customary System:
US customary system is the measurement system used in United States and a few caribbean countries. It's derived from the
old English measurement system similar to the imperial system but it was used in US before the imperial system was
defined in 1824, that's why most of the measurement unit names are the same but the values might be sligtly different,
especially for the weight and volume units. In 1832, it was officially accepted to be used by customs officials at US ports and
missed the opportunity to adopt metric system (originated in 1790 in France) as early as the 19th century. Later, in 1893,
many units were redefined in terms of meter and kilogram (imported from metric system) and redefined again in 1959 by the
international yard and pound agreement between six nations (US, UK, Canada, Australia, New Zealand and South Africa)
so that the yard is redefined to be as exactly 0.9144 meter and the pound as exactly 0.45359237 kilogram.
Metrication in US is not officially enforced unlike the other nations. US customary units are commonly used in
everyday life but for science, military and medicine, metric units are mostly used.
Metric system is a decimalized measurement system created in 1790 during the French revolution for the purpose of creating a
measurement system for everybody. The base length unit was metre (definition was replaced later in 1983), the volume unit was
litre (one thousandth of a cubic metre) and the unit of mass was kilogram (mass of one litre of water). The kilogram and metre
prototypes were kept by French government until 1875. In 1875, Metre Convention (Treaty of the Metre) has been signed by the
17 countries for the purpose of administering the maintenance and the development of metric standards globally.
Three international organizations were born. They are General Conference on Weights and Measures (decison making organization,
meets in every 4-6 years to discuss the new developments on metric system), International Committee for Weights and Measures
(18 high scientific standing individuals from member countries to advise on technical matters) and BIPM (International Bureau
of Weights and Measures to ensure the uniformity of metric weights and measures around the world). After 1875,
the prototypes are kept at the office of BIPM in France.
The unit names are based on adding prefixes "centi", "kilo' etc as decimal multipliers which makes metric system very easy
compared to the other measurement systems since to convert between the units, all you have to do is multiplying by a decimal.
For example, to calculate how many centimeters in a meter, all you have to do is multiply it by 100 since "centi" denotes
a factor of one hundredth in metric system. In imperial or US customary, to calculate how many inches in a mile, you
must know how many inches in a foot, then how many feet in a mile and then multiply these two results to find your answer
which is a kind of difficult for many people.
Here are the metric prefixes and their symbols:
Metric prefixes and symbols
SI - International System of Units:
Metric system was based on the metre and kilogram standards, but was not enough for all types of physics measurements, so
1960 SI (International System of Units) was born. It is an evolving measurement system which means the units are redefined
as needed and new ones added. SI is the world's mostly used measurement system, adopted globally except United States,
Burma and Liberia.
There are seven base units in SI system. They are metre for length, kilogram for mass, second for time, ampere for
electric current, kelvin for temperature, candela for luminous intensity and mole for amount of substance. All the other
units are based on these units and they are called derived units.