Conversion Calculator
 Short history of units  from feet to meters
 Different systems of measurement
 Prefixes  metric conversion table
 How to use the measurement conversion calculator
 Temperature conversion calculator
 Length conversion calculator
 Area conversion calculator
 Volume conversion calculator
 Weight conversion calculator
Our measurement conversion calculator includes five unit converters: a temperature conversion calculator, a length conversion calculator, an area conversion calculator, a volume conversion calculator, and a weight conversion calculator. The unit conversion calculator includes numerous units, so you can easily switch between the metric conversion, the imperial system, and the United States customary units.
Go right ahead to convert Celsius to Fahrenheit, feet to meters, pounds to kilograms (lbs to kg), and even light years to Sun radii! This measurement converter is particularly useful if you need to convert units of various types, so you don't need to switch between different converters all the time.
The conversion calculator is divided into "metric," "imperial/US," and "other" sections, so you can learn which units belong to which system, and focus on just one type, if, for example, you need just a metric conversion calculator.
The text below includes a few examples of conversion, a metric conversion table, and more.
Short history of units  from feet to meters
Long time ago, before globalisation began, but after humans had come down from the trees, measurement systems were needed for communication and trade. These early systems were, were so to speak, "downtoearth"  they were named after parts of the body, vessels, and other basic elements of everyday life. For instance, in Poland, people used: łokieć (ell), stopa (foot), dłoń (palm), palec (finger), and ziarno (grain).
Units were defined locally. Other than the Polish, many nations (including England, Greece, Rome, China, and France) used the foot as a part of their measurement system, but its size varied, even from city to city.
The Finns were inventive enough to come up with more extravagant units:
 peninkulma – the furthest distance from which a barking dog can be heard (c. 10 km)
 poronkusema – the distance a reindeer could travel without stopping to urinate (c. 7.5 km)
 tynnyrinala – the area (of field) that could be sown with one barrel of grain (4936.5 m2)
As the world became more and more interconnected, the need for one universal system grew. Imagine if scientists across the globe had to translate units into local ones, like French pied du roi (king's foot).
To cut a long story short, nations began to unify their units, as it made communication and trade simpler. The Enlightenment and the French Revolution gave rise to the metric system, which preceded to spread around the world.
Different systems of measurement
The metric system is now used in almost every countries. It is arranged around the decimal system, and in which the basic units are taken from the natural world (e.g., the meter is based on the dimensions of Earth). Its modern (i.e., far more developed than the version from the 18th century) form is The International System of Units (SI).
US customary units are still the primary system of measurement in the US and are used to some extent in Canada and Liberia.
In the UK the imperial units are still in use. Like US units, they derive from earlier English units. Although the two systems use the same names of units, they have different values. So be careful, UK gallon is not the same as US gallon.
Prefixes  metric conversion table
To understand metric conversion, it is useful to know what SI unit prefixes mean. Take a look at the metric conversion chart below:
Prefix  Symbol  Factor  

tera  T  10^{12}  1,000,000,000,000 
giga  G  10^{9}  1,000,000,000 
mega  M  10^{6}  1,000,000 
kilo  k  10^{3}  1,000 
hecto  h  10^{2}  100 
deca  da  10^{1}  10 
    10^{0}  1 
deci  d  10^{1}  0.1 
centi  c  10^{2}  0.01 
milli  m  10^{3}  0.001 
micro  µ  10^{6}  0.000,001 
nano  n  10^{9}  0.000,000,001 
pico  p  10^{12}  0.000,000,000,001 
How to interpret this metric conversion chart? For example, one megabyte is equal to million bytes:
1 MB = 1,000,000 B
Expressed in scientific notation:
1 MB = 10^{6} B
So, any time you see a unit in this form:
prefix + base unit
like "Megabyte," know that it's equal to the base unit multiplied the appropriate number of times.
A few more examples:
1 hectoliter = 100 liters
1 decagram = 10 grams
1 kilometer = 1,000 meters
1 nanosecond = 10^{9} second
How to use the measurement conversion calculator

Choose the type of conversion  select the temperature, length, area, volume, or weight converter.

If your desired unit is not displayed, choose it from the list of units (e.g., click °C and change it to °R) or switch to the advanced mode to show more variables.

Enter the value you'd like to calculate into the appropriate unit field.

Read the results of conversion.
Temperature conversion calculator
The temperature converter includes the following units:
 Celsius
 Fahrenheit
 Kelvin
 Rankine
 Delisle
 Newton
 Réaumur
 Rømer
If you want to know more about temperature and its conversion, or need to see a temperature conversion chart, check out our separate temperature converter.
Length conversion calculator
The length converter includes following units:
 ångström
 picometers
 nanometers
 micrometers
 millimeters
 centimeters
 decimeters
 meters
 meters and centimeters
 kilometers
 thousandths of an inch
 inches
 feet
 feet and inches
 yards
 miles
 nautical miles
 Sun radii
 light years
 astronomical units
 parsecs
How to convert the metric length units?
Earlier, we discussed metric unit prefixes. So, if you want to know how many meters are in one kilometer, just remember "kilo" means "thousand". What if you wanted to answer the opposite question?  how many kilometers are in a meter? The answer is the multiplicative inverse: onethousandth  1/1000.
Finally, the third scenario  you want to switch between units where both of them are not the base units e.g., from decagrams to micrograms. To do that:

Convert the first unit (dag) to the basic unit (g):
1 dag = 10 g

Convert the basic unit (g) to the second unit (µg):
1 g = 10^{6} µg

Multiply two results:
1 dag = 10 * 10^{6} µg
1 dag = 10^{7} µg
For a conversion table, and more information (how many feet in a meter, a definition of a meter, etc.) about length, see the length converter.
Area conversion calculator
The area conversion calculator includes the following units:
 square millimeters
 square centimeters
 square decimeters
 square meters
 square kilometers
 ares
 decares
 hectares
 square inches
 square feet
 square yards
 square miles
 acres
Metric area unit conversion
Converting between metric area units is slightly more difficult than converting between length units. Let's answer the question  how many square meters are in one square kilometer? Remember prefixes? Kilo = thousand, but 1 km^{2} is NOT equal to 1,000 m^{2}. Why?
First, what is a square meter? You can imagine it as a square with a side equal to 1 m:
m^{2} = m * m
Let's see how many square meters would fit in one square kilometer:
1 km^{2} = 1 km * 1 km
1 km^{2} = 1,000 m * 1,000 m
1 km^{2} = 1,000,000 m^{2} = 10^{6} m^{2}
One square kilometer equals one million square meters. To know it, you can simply square the "prefix value":
kilo = 1000
kilo^{2} = 1000^{2}
kilo^{2} = 1,000,000
To find out more, go to our area converter.
Volume conversion calculator
The volume conversion calculator includes following units:
 cubic nanometers
 cubic micrometers
 cubic millimeters
 cubic centimeters
 cubic decimeters
 cubic meters
 cubic kilometers
 cubic inches
 cubic feet
 cubic yards
 cubic miles
 milliliters
 centiliters
 liters
 US fluid ounces
 UK fluid ounces
 US pints
 UK pints
 US quarts
 UK quarts
 US gallons
 UK gallons
 US customary cups/glasses (236.59ml)
 tablespoons (15ml)
 teaspoons (5ml)
Metric volume unit conversion
Switching between cubic SI units is analogous to squared units, only the "prefix value" is cubed, not squared.
For example, how many cubic centimeters are in thirteen cubic meters?
m^{3} = m * m * m
1 m = 100 cm
13 m^{3} = 13 * 100 cm * 100 cm * 100 cm
13 m^{3} = 13,000,000 cm^{3}
If you're interested in converting imperial or US units, see the volume conversion chart.
Weight conversion calculator
The weight conversion calculator includes following units:
 micrograms
 milligrams
 grams
 decagrams
 kilograms
 metric tons
 ounces
 pounds
 stones
 US tons (short tons)
 UK tons (long tons)
 grains
 drachms
 weights of the Earth
 weights of the Sun
 electron rest mass
 proton rest mass
 neutron test mass
 atomic mass units
 Troy ounces
Metric weight unit conversion
Converting weight units is analogous to length conversion  a microgram is 0.000001 of a gram because "micro" means "0.000001" and gram is the base unit.
If you'd like to read the explanation of switching between measurement systems (convert lbs to kg, m to in, etc.), check out the separate weight converter.