Updated July 1, 2026

Unit conversion reference

A quick lookup of everyday conversion factors. Multiply the source value by the factor to get the target unit. Temperature uses a formula rather than a single factor.

Length

From	To	Multiply by
`kilometers`	`miles`	`0.621371`
`miles`	`kilometers`	`1.609344`
`meters`	`feet`	`3.28084`
`feet`	`meters`	`0.3048`
`centimeters`	`inches`	`0.393701`
`inches`	`centimeters`	`2.54`

Mass

From	To	Multiply by
`kilograms`	`pounds`	`2.204623`
`pounds`	`kilograms`	`0.453592`
`grams`	`ounces`	`0.035274`
`ounces`	`grams`	`28.349523`

Temperature

Temperature needs a formula, not a single factor.

Celsius    -> Fahrenheit :  F = C * 9/5 + 32
Fahrenheit -> Celsius    :  C = (F - 32) * 5/9
Celsius    -> Kelvin     :  K = C + 273.15

Exact vs approximate1 inch = 2.54 cm and 1 mile = 1.609344 km are exact by definition. Most others (like km to miles) are rounded, so expect tiny differences at high precision.

References

Questions

How do I convert kilometers to miles?

Multiply the kilometers by 0.621371. For example, 10 km x 0.621371 = 6.21 miles.

How do I convert Celsius to Fahrenheit?

Multiply by 9/5 and add 32. For example, 20 C x 9/5 + 32 = 68 F.