Length Converter
Convert miles, yards, feet, inches, kilometers, meters, centimeters, millimeters, micrometers, nanometers, and nautical miles in one place. Enter a measurement, choose your units, and get an instant result.
Convert Length Instantly
Edit either number, change a unit, or swap the direction of the conversion.
1 mi equals 1.609344 km
Popular length conversions
How to Use the Length Converter
This tool converts measurements between metric, imperial, US customary, and nautical length units. You do not need a different calculator for each pair of units: the dropdowns let you select any supported combination.
Enter a measurement
Type your number in the From box. You can enter whole numbers, decimals, or scientific notation for very small measurements.
Select the units
Choose a source and destination unit. Use Swap to reverse the conversion, or edit the To value to calculate backward.
Use your result
Read the answer, copy it, or compare several values in the automatically updated conversion table below.
Length Conversion Formula
To change a measurement from one length unit to another, multiply the original number by the conversion factor. Each factor is based on how the two units relate to the meter. Using the meter as the common reference keeps all supported combinations consistent.
General formula
Converted length = Original length × Conversion factorWorked example for your selected units
5 miles × 1.609344 = 8.04672 kilometers.
For example, one international mile equals exactly 1,609.344 meters. Because one kilometer equals 1,000 meters, one mile equals 1.609344 kilometers.
When your destination unit is smaller, the converted number usually gets larger. For example, one meter contains 100 centimeters. When the destination is larger, the number usually gets smaller: 100 centimeters equals one meter. The length itself does not change; only the number and unit used to describe it change.
Length Conversion Table
Use this chart to compare common values for the units selected in the calculator. Change either dropdown and the table updates automatically, so you can check multiple measurements without entering each one.
| Miles (mi) | Kilometers (km) |
|---|---|
| 1 | 1.609344 |
| 2 | 3.218688 |
| 5 | 8.04672 |
| 10 | 16.09344 |
| 25 | 40.2336 |
| 50 | 80.4672 |
| 100 | 160.9344 |
| 1000 | 1,609.344 |
Values may be displayed with rounded digits to keep the chart readable. The tool uses the defined unit factors when calculating.
Metric, Imperial, and Nautical Length Units
The metric system uses units related by powers of ten. Moving between kilometers, meters, centimeters, and millimeters is therefore straightforward. Imperial and US customary measurements use different relationships: a foot has 12 inches, a yard has 3 feet, and an international mile has 5,280 feet. Nautical miles are generally used for distances at sea and in aviation.
The following reference chart gives the length of each supported unit in meters. These values are sufficient to convert between any pair shown in the calculator.
| Unit | Symbol | Equivalent in meters |
|---|---|---|
| Mile | mi | 1,609.344 m |
| Yard | yd | 0.9144 m |
| Foot | ft | 0.3048 m |
| Inch | in | 0.0254 m |
| Kilometer | km | 1,000 m |
| Meter | m | 1 m |
| Centimeter | cm | 0.01 m |
| Millimeter | mm | 0.001 m |
| Micrometer | µm | 0.000001 m |
| Nanometer | nm | 0.000000001 m |
| Nautical mile | nmi | 1,852 m |
When should you use each measurement system?
Kilometers are useful for longer road distances, while meters and centimeters are practical for building dimensions, everyday objects, and classroom measurements. Millimeters are common for small parts and tolerances. Micrometers and nanometers describe much smaller scales, such as microscopic structures and wavelengths. Feet, inches, yards, and miles are still common in the United States and in particular industries elsewhere.
Use the unit specified by your assignment, drawing, product specification, or reference source. A correct conversion does not always imply that a measurement was precise to every displayed decimal place.
How Accurate Is This Length Converter?
For these 11 units, the converter uses fixed relationships with the meter. The international inch, foot, yard, mile, and nautical mile have defined metric equivalents. In ordinary use, these are not estimates based on geography or material properties. That makes length conversion different from a tool where the result depends on temperature, density, or a changing exchange rate.
Computer arithmetic and display formatting still have limits. This calculator preserves more digits internally than it shows on screen and switches to scientific notation for extremely small or large numbers. If a measurement comes from a ruler marked only in millimeters, adding many decimal places does not improve the accuracy of the original reading.
For technical or regulated work, use the required measurement standard and round to the appropriate number of significant figures. For everyday comparisons, the displayed result is normally more than sufficient.
Frequently Asked Questions
How many conversion combinations does this tool support?
It supports 11 units. You can convert from any one unit to any of the other 10, making 110 directional conversion combinations. You can also select the same unit on both sides when you simply want to check a value.
How do I convert miles to kilometers?
Multiply the number of international miles by 1.609344. For example, 10 miles equals 16.09344 kilometers. Select Miles under From and Kilometers under To to calculate other values.
How many centimeters are in one inch?
One international inch equals exactly 2.54 centimeters. For the reverse conversion, divide centimeters by 2.54 to find inches.
Can I enter feet and inches together, like 5 feet 8 inches?
This converter handles one unit at a time, such as 5.6667 feet or 68 inches. For two separate inputs, use our dedicated Feet and Inches to Centimeters or Feet and Inches to Meters tool, linked below.
Can I convert nanometers and micrometers?
Yes. One micrometer equals 1,000 nanometers. Choose Micrometers and Nanometers in either order. Very small answers may be displayed in scientific notation to avoid a long string of zeros.
Is a nautical mile the same as a regular mile?
No. A nautical mile equals exactly 1,852 meters, while an international mile equals exactly 1,609.344 meters. Choose the correct mile unit before converting distances used in navigation.
Does converting a measurement change its accuracy?
No. Unit conversion changes how a measurement is expressed, not how precisely it was measured. Round your final result according to the accuracy of the source measurement.
Related Length and Measurement Tools
Need to enter a measurement as feet plus inches rather than as one decimal number? These tools use a separate input for each part of the measurement.
Reference: The unit relationships used here follow the defined international inch and yard, SI metric prefixes, and the 1,852-meter international nautical mile. For definitions, see the NIST SI units reference and the BIPM SI Brochure.