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)
Temperature does not use a single multiplier because each scale has an offset, so the calculator applies a dedicated formula for each pair:
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 Solve for menu sets the measurement category, which controls the base unit and the list of available units. The From and To menus pick the units on each side of the conversion. The value field holds the number you want to convert. Swap units flips the source and target so you can reverse a conversion without retyping. The Show equivalents option lists your value in every unit in the selected category at once.
Common Conversion Factors
These factors show how each unit compares to its category base unit. The calculator stores values like these and applies them with the formula above.
| 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) | 0.028349523 kg |
| 1 US gallon | Volume (m3) | 0.003785412 m3 |
| 1 liter | Volume (m3) | 0.001 m3 |
| 1 mile per hour | Speed (m/s) | 0.44704 m/s |
Temperature scales use offsets instead of factors, so they convert with the formulas in the section above rather than a single multiplier.
| 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. Turn on the Show equivalents option before you calculate, and the result lists your value expressed in every unit available in the selected category, alongside the main converted result.
Why is my temperature result rejected? The calculator blocks results below absolute zero, which is the lowest possible temperature. If you enter a value that would fall below absolute zero in the target scale, it returns an error instead of an impossible reading.
