Length Converter

Popular Length conversions

About length units

Length measures distance in one dimension. The metre is the SI base unit, defined since 1983 as the distance light travels in a vacuum in 1/299,792,458 of a second. Metric units (mm, cm, m, km) scale by powers of ten, which makes conversion within the system a simple decimal shift.

Imperial and US customary units — inch, foot, yard and mile — are now defined exactly in terms of the metre (1 inch = 0.0254 m exactly), so conversions are precise rather than approximate. The nautical mile (1,852 m) is defined as one minute of latitude and is used in sea and air navigation.

Handy Length reference points

• 1 mi ≈ 1.609 kmMile to kilometre
• 1 in = 2.54 cmInch to centimetre exactly
• 42.195 kmMarathon distance
• 8,849 mHeight of Mount Everest
• 1,852 mOne nautical mile

Supported Length units

• Millimeters (mm) — One thousandth of a metre.
• Centimeters (cm) — One hundredth of a metre; a fingernail is about 1 cm wide.
• Meters (m) — The SI base unit of length.
• Kilometers (km) — One thousand metres, used for road and travel distances.
• Inches (in) — Exactly 2.54 cm, used in the US, UK and for screens.
• Feet (ft) — 12 inches (0.3048 m), used for height and short distances.
• Yards (yd) — 3 feet (0.9144 m), used in sport and fabric.
• Miles (mi) — 1,609.344 m, the statute mile for road distances.
• Nautical miles (nmi) — 1,852 m, one minute of latitude, used at sea and in the air.