Length Unit Converter
Convert between different length and distance units including meters, feet, inches, and more
Conversion Result
Converted to All Units
Common Length Conversions
Metric to Imperial
- • 1 meter = 3.28084 feet
- • 1 kilometer = 0.621371 miles
- • 1 centimeter = 0.393701 inches
- • 1 millimeter = 0.0393701 inches
Imperial to Metric
- • 1 foot = 0.3048 meters
- • 1 mile = 1.60934 kilometers
- • 1 inch = 2.54 centimeters
- • 1 yard = 0.9144 meters
Understanding Length Units
Length is one of the fundamental physical quantities used to measure the distance between two points. Throughout history, various systems of measurement have been developed, leading to the two major systems used today: the International System of Units (SI), based on the meter, and the Imperial system, based on the foot and mile. The meter was originally defined in 1793 as one ten-millionth of the distance from the equator to the North Pole, and is now defined by the speed of light in vacuum.
Metric System (SI)
- Kilometer (km): 1,000 meters. Used for measuring large distances like roads and geography.
- Meter (m): The SI base unit of length, defined as the distance light travels in vacuum in 1/299,792,458 of a second.
- Centimeter (cm): 1/100 of a meter. Commonly used for body measurements and small objects.
- Millimeter (mm): 1/1,000 of a meter. Used in engineering, manufacturing, and precision work.
- Micrometer (µm): 1/1,000,000 of a meter. Used in science and technology for microscopic measurements.
- Nanometer (nm): 1/1,000,000,000 of a meter. Used in nanotechnology and measuring wavelengths of light.
Imperial / US Customary System
- Mile (mi): 5,280 feet (1,609.344 meters). Used for road distances in the US, UK, and a few other countries.
- Yard (yd): 3 feet (0.9144 meters). Used in sports fields and fabric measurement.
- Foot (ft): 12 inches (0.3048 meters). Commonly used for height, room dimensions, and altitude.
- Inch (in): 1/12 of a foot (2.54 centimeters). Used for screen sizes, small measurements, and engineering.
Nautical & Astronomical Units
Nautical Mile (nmi)
Equal to 1,852 meters (approximately 1.15078 statute miles). Based on one minute of arc of latitude along the Earth's meridian. Used in maritime and air navigation worldwide.
Astronomical Unit (AU)
Approximately 149,597,870,700 meters, roughly the mean distance from Earth to the Sun. Used for measuring distances within the solar system.
Light-Year (ly)
Approximately 9.461 × 1015 meters, the distance light travels in one Julian year. Used for expressing distances between stars and galaxies.
References
The conversion factors used in this calculator are based on internationally recognized standards and definitions:
Note: All conversions use exact or internationally accepted conversion factors. The meter is defined by the International Bureau of Weights and Measures (BIPM) as the distance light travels in vacuum in exactly 1/299,792,458 of a second. Imperial and US customary units are defined relative to the meter since 1959 (1 inch = 25.4 mm exactly).
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