Distance & Length Unit Converter
Convert values between Metric, Imperial, US Customary, and Nautical distance measurement systems.
Equivalent Lengths Across Common Units:
Comprehensive Guide to Length and Distance Measurement
Length is defined as the most extended dimension of an object, or the linear space between two points. Throughout human history, measurements of distance were based on human body proportions (such as the cubit, foot, pace, or thumb width). The modern era standardized these measurements into two dominant global systems: the International System of Units (SI) and the Imperial / US Customary System.
The Fundamental Metric Standard
Under the International Bureau of Weights and Measures (BIPM), the meter (m) is the fundamental SI base unit of length. Since 1983, the meter has been defined by fixing the numerical value of the speed of light in vacuum ($c$) to exactly 299,792,458 meters per second. All decimal subdivisions and multiples (millimeters, centimeters, kilometers, micrometers, and nanometers) derive directly from powers of ten.
The 1959 International Yard and Pound Agreement
To eliminate minor discrepancies between British and American imperial definitions, the United States, United Kingdom, Canada, Australia, New Zealand, and South Africa signed the 1959 agreement, defining:
- 1 international yard = exactly 0.9144 meters
- 1 international foot = exactly 0.3048 meters (12 inches)
- 1 international inch = exactly 25.4 millimeters (2.54 cm)
- 1 international statute mile = exactly 1,609.344 meters (5,280 feet)
Standard Distance Conversion Factors
| Unit Name | Symbol | Equivalent in Meters (m) | Equivalent in Feet (ft) |
|---|---|---|---|
| Millimeter | mm | 0.001 m | 0.00328084 ft |
| Centimeter | cm | 0.01 m | 0.0328084 ft |
| Meter (SI Base) | m | 1.0 m | 3.28084 ft |
| Kilometer | km | 1,000 m | 3,280.84 ft (0.621371 mi) |
| Inch | in | 0.0254 m | 0.0833333 ft |
| Foot | ft | 0.3048 m | 1.0 ft |
| Yard | yd | 0.9144 m | 3.0 ft |
| Mile (Statute) | mi | 1,609.344 m | 5,280 ft |
| Nautical Mile | nmi / NM | 1,852 m | 6,076.12 ft |
Conversion ratios are exact constants defined by the BIPM SI Brochure (9th Edition) and NIST Special Publication 811 (1 international yard = 0.9144 m; 1 international foot = 0.3048 m).