Length and Distance Converter
Millimeters through nautical miles in one tool, plus dedicated converters for the pairs people look up most.
Most used length tools
Height Converter
Centimeters to feet and inches, with the rounding boundaries made explicit.
Cm to Inches
With the nearest tape-measure fraction.
Mm to Inches
Down to 1/64, with the error shown.
Km to Miles
Road and race distances.
Convert every unit at once
Enter a number.
Every length converter on this site
Reference table
| Unit | In meters | Exact? |
|---|---|---|
| 1 millimeter | 0.001 m | Exact |
| 1 centimeter | 0.01 m | Exact |
| 1 kilometer | 1000 m | Exact |
| 1 inch | 0.0254 m | Exact |
| 1 foot | 0.3048 m | Exact |
| 1 yard | 0.9144 m | Exact |
| 1 mile | 1609.344 m | Exact |
| 1 nautical mile | 1852 m | Exact |
Everything here is exact
Unusually for a conversion category, every relationship above is exact by definition rather than measured. The inch has been exactly 2.54 centimeters since 1959, and the yard, foot, mile and nautical mile all follow from metric definitions.
That doesn't make every converted answer exact. Your input is usually a measurement with its own precision, and reporting more digits than it justifies is misleading. The exact versus rounded guide covers how many to keep.
The one exception, and it expired
The US survey foot, used in American land surveying, was larger than the international foot by about two parts per million. NIST and NOAA deprecated it on 31 December 2022; since 1 January 2023 it is obsolete and the international foot, now called simply the foot, applies to all US surveying and mapping.
It is retained only for legacy applications such as the State Plane Coordinate Systems of 1927 and 1983. Everything on this site uses the international foot, which is now simply the correct one.
Common questions
Is the inch exactly 2.54 centimeters?
Yes. It has been defined as exactly 2.54 centimeters since the 1959 international yard and pound agreement, and every other imperial length on this site follows from that definition.
What is the difference between a mile and a nautical mile?
A statute mile is 1,609.344 meters. A nautical mile is 1,852 meters, defined as one minute of latitude, which is why it is used for marine and air navigation.
Which foot does this tool use?
The international foot of exactly 0.3048 meters. The US survey foot, deprecated at the end of 2022, was larger by about two parts per million and isn't used here.
Why do my converted measurements have so many decimal places?
Because the arithmetic produces them, not because the precision is real. A converted figure should carry no more significant digits than the measurement you started with.
Sources
- U.S. Survey Foot: Frequently Asked Questions. National Institute of Standards and Technology. Source for the 31 December 2022 deprecation, the obsolete status from 1 January 2023, and the retention of the survey foot for legacy state plane coordinate systems only.
- NIST Guide to the SI, Appendix B: Conversion Factors. National Institute of Standards and Technology. Source for every conversion factor used by this tool, and for which factors are exact rather than rounded.