Convert between kilometers, miles, meters, feet, inches, centimeters, millimeters, and yards. Enter a value in the calculator below, or browse the popular converters and reference table further down.
Length conversion is one of the most common unit calculations. The metric system (meters, centimeters, kilometers) is used by most of the world, while the imperial system (feet, inches, miles, yards) is standard in the United States and partially in the UK. The exact relationships between these systems are fixed by international agreement: 1 inch equals exactly 2.54 centimeters, and all other length conversions derive from this definition.
Common use cases include converting kilometers to miles for travel distances, meters to feet for building measurements, and inches to centimeters for product dimensions. Each converter on this page shows the formula and a step-by-step breakdown so you can verify the math.
Results above are rounded for readability. Each converter page shows the full-precision factor. For complete formulas with worked examples, visit the formulas hub.
Metric length units (meters, centimeters, kilometers) are based on powers of 10 and are used by most countries. Imperial units (feet, inches, miles, yards) are used primarily in the US and UK. The two systems have fixed conversion factors: 1 inch = 2.54 cm, 1 foot = 0.3048 m, 1 mile = 1.609344 km.
There are exactly 5,280 feet in one mile. To convert miles to feet, multiply the number of miles by 5,280. See the miles to feet converter.
Some are exact by definition: 1 inch = exactly 2.54 cm, 1 foot = exactly 0.3048 m. Others like 1 mile = 1.609344 km are exact but produce long decimals when inverted. All conversions on UnitCompare use the full-precision standard factors.
For everyday estimates, rounded factors work fine (1 km is roughly 0.6 miles, 1 meter is roughly 3.3 feet). For engineering, construction, or scientific work, use the exact factors. Every converter on this page shows both the quick result and the precise formula.
