Calculate unit conversions across length, area, volume, mass, temperature, speed, and more with the measurement calculator.
Measurement Conversion Formula
Most measurement conversions multiply your value by the source unit’s factor and divide by the target unit’s factor. Both factors are stated relative to the category base unit (for example, the meter for length or the kilogram for mass).
R = V * (Ff / Ft)
- R = converted result in the target unit
- V = value you entered in the source unit
- Ff = conversion factor of the source unit (its size in base units)
- Ft = conversion factor of the target unit (its size in base units)
Absolute-temperature conversions may require an offset as well as a multiplier, so the calculator applies the formula for the selected scales:
F = C * 9/5 + 32
C = (F - 32) * 5/9
K = C + 273.15
- C = temperature in degrees Celsius
- F = temperature in degrees Fahrenheit
- K = temperature in kelvin
The Measurement category menu controls the available units. Choose the From and To units, enter the measurement value, and select Calculate. Changing category or From unit reinterprets the entered number; it does not convert that input automatically. To reverse a conversion, select the desired From and To units and enter the value to convert. The Equivalent units setting adds every unit in that category to the calculation details.
Common Conversion Factors
These factors show how each unit compares to its category base unit. Feet and their powers use the international foot; pounds and ounces are avoirdupois mass. US volume units are liquid/customary measures, including a 236.5882365 mL cup; the Imperial gallon is separate. Time uses 24-hour days and a 365.25-day Julian year. Calories are thermochemical and BTU is the International Table convention.
| Unit | Category | Value in base unit |
|---|---|---|
| 1 inch | Length (m) | 0.0254 m |
| 1 foot | Length (m) | 0.3048 m |
| 1 mile | Length (m) | 1609.344 m |
| 1 pound | Mass (kg) | 0.45359237 kg |
| 1 ounce | Mass (kg) | 0.028349523125 kg |
| 1 US gallon | Volume (m3) | 0.003785411784 m3 |
| 1 liter | Volume (m3) | 0.001 m3 |
| 1 mile per hour | Speed (m/s) | 0.44704 m/s |
Use the temperature formulas above for absolute readings. Temperature differences use scale factors without the absolute-reading offsets. The water reference points below are approximate values at standard atmospheric pressure (1 atm).
| Reference point | Celsius | Fahrenheit | Kelvin |
|---|---|---|---|
| Water freezes | 0 | 32 | 273.15 |
| Room temperature | 20 | 68 | 293.15 |
| Water boils | 100 | 212 | 373.15 |
Example Problems
Example 1: Length. You want to convert 10 feet to meters. The factor for feet is 0.3048 and the factor for meters is 1. Apply the formula: R = 10 * (0.3048 / 1) = 3.048 meters.
Example 2: Temperature. You want to convert 75 degrees Fahrenheit to Celsius. Use the Fahrenheit to Celsius formula: C = (75 – 32) * 5/9 ≈ 23.89 degrees Celsius.
Frequently Asked Questions
How does the calculator convert between units? Every unit in a category is defined by its size relative to a base unit, such as the meter for length. The calculator converts your value into the base unit, then converts the base value into the target unit. Temperature is the exception, since each scale has its own zero point and uses an offset formula.
Can I convert one value into several units at once? Yes. Set Show equivalents in every unit to Yes before calculating, then open Calculation details to see every unit available in the selected category. The main converted result remains first.
Why is my temperature result rejected? The calculator rejects absolute readings below 0 K: −273.15 °C, −459.67 °F or 0 °R. A reading exactly at absolute zero is allowed. This mode converts absolute readings, not temperature differences.
