What are length units?
Length units are used to measure distance or linear dimensions. Common units include meter (m), kilometer (km), centimeter (cm), mile (mi), yard (yd), foot (ft) and inch (in).
Short overview of main units
- Meter (m) — the base unit of length in the International System (SI). It is the standard for measuring length.
- Kilometer (km) — 1 km = 1000 m. Commonly used for road distances and geography.
- Centimeter (cm) — 1 cm = 0.01 m. Used for small measurements in everyday objects.
- Millimeter (mm) — 1 mm = 0.001 m. Used for precise small-scale measurements.
- Mile (mi) — 1 mi = 1609.344 m. Used in the US and UK for road distances.
- Yard (yd) — 1 yd = 0.9144 m. Used in some countries and in sports contexts.
- Foot (ft) — 1 ft = 0.3048 m. Common in construction and everyday usage in imperial systems.
- Inch (in) — 1 in = 0.0254 m. Used for small measurements, screens and printing.
How conversion works
Conversions are performed by using a factor relative to the base unit (meter). Examples:
- Convert 5 km to meters: 5 × 1000 = 5000 m.
- Convert 10 in to cm: convert to meters first (10 × 0.0254 = 0.254 m), then to cm (0.254 × 100 = 25.4 cm). This tool computes via relative factors so the result is the same.
- Convert 2 mi to km: 2 mi = 2 × 1609.344 m = 3218.688 m → divide by 1000 = 3.218688 km.
Usage tips
- Enter decimal numbers with a dot (e.g. 1.5).
- Use the ⇄ button to quickly swap source and target units.
- Results are rounded to 6 decimal places for readability.