How Length Conversion Works
Every length unit is defined as an exact multiple of the meter, the SI base unit. Converting is therefore one multiplication: express the value in meters, then in the target unit. Because the imperial units have exact metric definitions (1 in = 0.0254 m, 1 mi = 1,609.344 m), these conversions have no rounding error at all.
Convert 5 miles to kilometers: 5 × 1,609.344 m = 8,046.72 m = 8.047 km.
Common Length Conversions
| From | To | Multiply by |
|---|---|---|
| inches | centimeters | 2.54 (exact) |
| feet | meters | 0.3048 (exact) |
| yards | meters | 0.9144 (exact) |
| miles | kilometers | 1.609344 (exact) |
| meters | feet | 3.28084 |
| kilometers | miles | 0.621371 |
Frequently Asked Questions
How many centimeters are in an inch?
Exactly 2.54 cm — this is the international definition of the inch since 1959, so inch-to-centimeter conversions are exact, not approximations.
How do I convert kilometers to miles quickly?
Multiply by 0.621, or for a quick estimate multiply by 5/8. So 80 km ≈ 50 miles. Going the other way, multiply miles by 1.609.
How many feet are in a meter?
About 3.281 feet. A meter is slightly longer than a yard (1 m = 1.094 yd).
Why do the US and UK still use miles?
Historical convention: road signage, land records and everyday speech were built around imperial units, and switching national infrastructure is costly. Science, medicine and industry in both countries use metric.
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The CalculatorsGuide Editorial Team. (2026). Length Converter. CalculatorsGuide. Retrieved from https://www.calculatorsguide.com/conversions/length-converter/