How the Conversion Calculator Works
The same quantity can be measured in many units: a distance in miles or kilometers, a weight in pounds or kilograms, a temperature in degrees Celsius or Fahrenheit. The Unit Conversion Calculator changes a value from one unit to another, in six categories: length, weight, temperature, area, volume and time.
How a conversion works
Every unit has a fixed size compared with the base unit of its category (the meter for length, the kilogram for weight, the square meter for area, the liter for volume and the second for time). To convert, the calculator does two steps:
value in base units = value x size of the "from" unit result = value in base units / size of the "to" unit
Example: 5 miles in kilometers. One mile is 1,609.344 meters, so 5 miles are 8,046.72 meters, and one kilometer is 1,000 meters, so the result is 8.04672 km.
The sizes are the exact legal definitions. For example, 1 inch is exactly 2.54 cm, 1 mile is exactly 1,609.344 meters, 1 pound is exactly 0.45359237 kg and 1 US gallon is exactly 3.785411784 liters. The result is shown with up to 10 digits.
Length
| Unit | Size in meters |
|---|---|
| 1 millimeter | 0.001 |
| 1 centimeter | 0.01 |
| 1 inch | 0.0254 |
| 1 foot | 0.3048 |
| 1 yard | 0.9144 |
| 1 kilometer | 1,000 |
| 1 mile | 1,609.344 |
| 1 nautical mile | 1,852 |
The lengths cover a wide range, so this chart uses a log scale, where each step to the right is the same ratio (1 block is about 0.1 of a power of ten). Blue is less than a meter, green is a meter or more, and amber is a kilometer or more.
Millimeter █ 0.001 m Inch █████████ 0.0254 m Foot ████████████████ 0.3048 m Yard ███████████████████ 0.9144 m Meter ███████████████████ 1 m Kilometer ███████████████████████████████████████ 1,000 m Mile ████████████████████████████████████████ 1,609.344 m
Weight (mass)
| Unit | Size in kilograms |
|---|---|
| 1 gram | 0.001 |
| 1 ounce | 0.028349523125 |
| 1 pound | 0.45359237 |
| 1 stone (14 pounds) | 6.35029318 |
| 1 metric ton | 1,000 |
| 1 US ton (2,000 pounds) | 907.18474 |
A "ton" is not always the same. A metric ton (tonne) is 1,000 kg, a US ton is 2,000 pounds, and a UK ton is 2,240 pounds. The calculator lists the metric ton and the US ton.
Temperature
Temperature scales do not only differ by a factor. They also start at a different zero, so the calculator changes the value to degrees Celsius first, and from there to the unit that you want:
°F to °C: (F - 32) x 5 / 9 °C to °F: C x 9 / 5 + 32 K to °C: K - 273.15 °C to K: C + 273.15
| Point | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Water freezes | 0 °C | 32 °F | 273.15 K |
| Fridge | 4 °C | 39.2 °F | 277.15 K |
| Room | 20 °C | 68 °F | 293.15 K |
| Body | 37 °C | 98.6 °F | 310.15 K |
| Hot bath | 45 °C | 113 °F | 318.15 K |
| Water boils | 100 °C | 212 °F | 373.15 K |
The two scales are equal at -40 (-40 °C is -40 °F). The lowest possible temperature is absolute zero, which is -273.15 °C, -459.67 °F and 0 K. The calculator does not accept a lower value. Each block of the chart is 2.5 °C.
Water freezes █ 0 C = 32 F Fridge ██ 4 C = 39.2 F Room ████████ 20 C = 68 F Body ███████████████ 37 C = 98.6 F Hot bath ██████████████████ 45 C = 113 F Water boils ████████████████████████████████████████ 100 C = 212 F
Area
| Unit | Size in square meters |
|---|---|
| 1 square foot | 0.09290304 |
| 1 square yard | 0.83612736 |
| 1 hectare | 10,000 |
| 1 acre | 4,046.8564224 |
| 1 square kilometer | 1,000,000 |
| 1 square mile | 2,589,988.110336 |
1 acre is 43,560 square feet, or about 0.4047 hectares. A square mile is 640 acres.
Volume
The US units are used for the cup, the pint, the quart and the gallon. A UK (imperial) pint or gallon is a different size (an imperial gallon is 4.546 liters), so use a converter for imperial units if you need them. In one US gallon there are:
Gallon █ 1 Quarts █ 4 Pints ███ 8 Cups █████ 16 Fluid ounces ████████████████████████████████████████ 128
Each block is 3.2 units. The kitchen units follow simple steps: 1 gallon = 4 quarts = 8 pints = 16 cups = 128 fluid ounces, and 1 tablespoon = 3 teaspoons.
Time
1 minute is 60 seconds, 1 hour is 3,600 seconds, 1 day is 86,400 seconds and 1 week is 604,800 seconds. A year is taken as 365.25 days (31,557,600 seconds), which is the average of the years of the calendar with the leap years.
Tips
- Use the swap button to turn a conversion around.
- Read the units in the list. The names say if a unit is US or something else.
- Check very big or very small answers. Numbers below 0.000001 or above 1,000,000,000,000,000 are shown with an exponent, for example 1.5e-7.
What this calculator does not include
- Imperial (UK) volume units, and speed, pressure, energy, data or currency units. Use the special converters for them.
- Negative weights, areas, volumes and times. They are not accepted.
This tool gives conversions based on the standard definitions of the units. For work in science, medicine or trade, check the result.