Length Converter: Meters, Feet, Inches, Miles & More
A length converter for meters, kilometers, centimeters, millimeters, inches, feet, yards, and miles, with exact results and a visual bar chart comparison.
Universal Length Converter
Convert between different units of length with this simple tool. Enter a value and select a unit to see conversions to all other units.
Conversion Results
Visual Comparison
Documentation
Length Converter: Meters, Feet, Inches, Centimeters, and More
A length converter changes a distance measurement from one unit into another, such as meters into feet or inches into centimeters. This tool converts between eight units of length: millimeters, centimeters, meters, kilometers, inches, feet, yards, and miles.
Why length has more than one unit
Two measurement systems are in common use today. The metric system, used by most of the world, is based on the meter and scales by powers of ten. The imperial and US customary system, used mainly in the United States, is based on the inch, foot, yard, and mile. Because the two systems developed separately, converting between them requires a formula rather than simple counting.
How to calculate a length conversion
Conversion factors
Every unit of length can be written as a fixed number of meters. The table below lists the factor the calculator uses for each unit.
| Unit | Symbol | Equal to |
|---|---|---|
| Millimeter | mm | 0.001 m |
| Centimeter | cm | 0.01 m |
| Meter | m | 1 m (base unit) |
| Kilometer | km | 1,000 m |
| Inch | in | 0.0254 m |
| Foot | ft | 0.3048 m |
| Yard | yd | 0.9144 m |
| Mile | mi | 1,609.344 m |
The inch, foot, yard, and mile values are exact by international agreement. A meter is defined by the distance light travels in a vacuum in 1/299,792,458 of a second.
The formula
To convert a value from one unit to another, the calculator first turns it into meters, then turns that meter value into the target unit:
value in meters = value × (factor of the starting unit)
result = value in meters ÷ (factor of the target unit)
This two-step method needs only one factor per unit instead of a separate formula for every possible pair of units.
Worked example
Convert 5 feet to meters.
- Multiply by the foot factor: 5 × 0.3048 = 1.524 meters.
Convert 1.524 meters back to feet, to check the answer.
- Divide by the foot factor: 1.524 ÷ 0.3048 = 5 feet.
A second example: convert 10 kilometers to miles.
- Turn kilometers into meters: 10 × 1,000 = 10,000 meters.
- Divide by the mile factor: 10,000 ÷ 1,609.344 ≈ 6.2137 miles.
How to use the converter
Enter a length in the input box and choose its unit from the dropdown menu. The calculator immediately shows the same length in all seven other units, with no button to press. Each result can be copied with the "Copy" button next to it. A bar chart below the results shows the same length across every unit, so the size differences are visible at a glance. Entering a negative number produces an error message and no result, since a length cannot be negative.
How results are rounded
The displayed number of decimal places depends on the size of the result. Values of 1,000 or more show two decimal places. Values from 10 up to 1,000 show three. Smaller values show four, five, or six decimal places as the number gets closer to zero. Results below 0.001 switch to a compact scientific form, such as 1.234560 × 10^-4, instead of a long string of leading zeros. The full, unrounded value is used internally and is what gets copied.
Metric and imperial: a short history
Historic units of length were often based on the human body: a foot, a hand span, or a forearm. Because bodies differ, these units differed too, which caused disputes in trade and building.
The imperial system used in English-speaking countries today grew out of these older units and was formally standardized in Britain in 1824. The United States adopted it and never fully switched away, so American measurements are still commonly given in feet, inches, and miles.
France introduced the metric system in 1799, defining the meter as one ten-millionth of the distance from the North Pole to the equator, measured along a line through Paris. The system's decimal structure made it far easier to scale up or down than measurement by body parts. Most countries had adopted the metric system by the 20th century.
Because the meter and the foot were fixed independently, converting between them rarely produces a round number. A 10-foot wall becomes 3.048 meters, not an even 3.
Where length conversion is used
Construction plans drawn in one country often specify metric measurements, while lumber and tools in the United States are marked in feet and inches, so a builder working across both needs accurate conversion. Manufacturing and machining have the same issue: a part designed in inches must be cut on a machine calibrated in millimeters, and a rounding mistake at that stage can make a part fail to fit. Online stores that ship internationally list package dimensions in both centimeters and inches, since carriers calculate shipping cost from size. Runners and cyclists compare distances measured in kilometers by GPS watches with race distances often given in miles, such as a marathon's 26.2 miles, equal to 42.195 kilometers.
Limits of this calculator
This tool uses the international foot and mile, standardized in 1959. A separate unit, the US survey foot, is slightly longer, at about 0.3048006 meters, and is still used in some older land surveys in the United States; the difference only matters over long distances. The tool also does not include the nautical mile, which is used in sea and air navigation and equals 1,852 meters, about 1.15 statute miles. Digital calculations use floating-point arithmetic, which can leave a tiny rounding error far beyond the precision needed for construction, DIY projects, or schoolwork; work that needs micron-level accuracy should be checked with specialized engineering software.
Frequently asked questions
How do I convert meters to feet?
Multiply the number of meters by 3.28084. For example, 5 meters equals 5 × 3.28084, or about 16.4042 feet.
How many inches are in a meter?
One meter equals about 39.3701 inches, found by dividing 1 by 0.0254.
How do I convert kilometers to miles?
Multiply kilometers by 0.621371. Ten kilometers equals about 6.21 miles. Going the other way, multiply miles by 1.60934 to get kilometers.
Why do metric-to-imperial conversions give long decimals?
The meter and the foot were defined independently of one another, so there is no simple whole-number relationship between them. Only a few conversions, such as 1 inch equal to exactly 2.54 centimeters, come out as round numbers.
Does this converter include nautical miles or the US survey foot?
No. It converts millimeters, centimeters, meters, kilometers, inches, feet, yards, and statute miles only. Nautical miles (1,852 meters) and the US survey foot (about 0.3048006 meters) are not included.
Does the converter work without an internet connection?
The calculation runs in the browser once the page has loaded, so no server request is needed for each conversion. Loading the page the first time still requires an internet connection.
References
- International Bureau of Weights and Measures (BIPM) — official SI unit definitions.
- NIST unit conversion guide — reference conversion factors.
- NIST: what is a meter? — the modern definition of the meter.