Conversion Factor Definition and Examples

What a Conversion Factor Is and How to Use It

A conversion factor is a numerical relation that lets you change from one unit into another.
A conversion factor is a numerical relation that lets you change from one unit into another. Gen Sadakane / EyeEm / Getty Images

A conversion factor is defined as a numerical ratio or fraction used to express a measurement given in one unit as another unit. A conversion factor is always equal to 1.

Examples of Conversion Factors

Examples of conversion factors include:

  • 1 minute / 60 seconds
  • 1000 grams / 1 kilogram
  • 4 quarts / 1 gallon

Remember, the two values must represent the same quantity as each other. For example, it's possible to convert between two units of mass (e.g., gram, pound), but you generally can't convert between units of mass and volume (e.g., grams to gallons).

Using a Conversion Factor

For example, to change a time measurement from hours to days, a conversion factor of 1 day = 24 hours.

time in days = time in hours x (1 day/24 hours)

The (1 day/24 hours) is a conversion factor.

Note that following the equal sign, the units for hours cancel out, leaving only the unit for days.