Miles to kilometers and back: 1 mile is exactly 1.609344 km
Runs in your browser. Nothing you type is sent anywhere. Checked against sources on 6 Oct 2026.To turn miles into kilometers, multiply by 1.609344: a mile is defined as exactly 1,609.344 meters. So 5 miles is 8.04672 km and a 26.2-mile marathon is 42.1648 km. Going the other way, one kilometer is 0.621371 miles, so a 10K race is 6.21 miles.
| Miles | Kilometers |
|---|---|
| 1 mi | 1.609344 km |
| 3.1 mi | 4.9889664 km |
| 5 mi | 8.04672 km |
| 10 mi | 16.09344 km |
| 13.1 mi | 21.0824064 km |
| 26.2 mi | 42.1648128 km |
| 50 mi | 80.4672 km |
| 100 mi | 160.9344 km |
The page opens on Length with Miles in the first box and Kilometers in the second.
Type the miles; the kilometers appear as you type (miles x 1.609344).
To go the other way, type in the Kilometers box instead (km x 0.621371).
Read yards, feet and meters for the same distance under Every unit.
Type in either box and the other follows; the table below lists common race and road distances.
The Unit Converter changes a number between metric, US and UK units of length, weight, volume, temperature, speed, area, data size and time. Type in either of the two boxes and the other one follows, so there is no button to press and no direction to choose. Under the boxes, the same amount is shown in every other unit of that kind.
Where the numbers come from. Every factor is a legal definition, not a rounded table value. NIST Special Publication 811 (the US Guide for the Use of the SI) defines the inch as exactly 2.54 cm, the foot as 0.3048 m, the mile as 1,609.344 m and the pound as exactly 0.45359237 kg. NIST Handbook 44 defines the US gallon as 231 cubic inches and the cup as 8 fluid ounces. The UK gallon is exactly 4.54609 liters. Temperature uses the SP 811 formulas: °F = °C × 1.8 + 32 and K = °C + 273.15. The Definitions tab lists each unit with its definition.
What this converter does not do: cups to grams for an ingredient (that needs a density; use Cups to Grams), Indian land units such as bigha and guntha (Land Area Converter), feet-and-inches arithmetic, shoe sizes or currency.
The rest of the article, and all 6 questions about Unit Converter, are on the Unit Converter page.
One mile is exactly 1.609344 kilometers, because the international mile is defined as 5,280 feet of 0.3048 meters each, or 1,609.344 meters. To go from kilometers to miles, multiply by 0.621371. A 10-kilometer race is therefore 6.21 miles, and a 26.2-mile marathon is 42.195 kilometers.
A kilogram is 2.20462262 pounds. The avoirdupois pound has been defined since 1959 as exactly 0.45359237 kilograms, and dividing 1 by that number gives the pounds in a kilogram. For a quick estimate, double the kilograms and add 10 percent: 50 kg is about 110 pounds, exactly 110.23.
No. A US gallon is 231 cubic inches, exactly 3.785411784 liters, and holds 128 US fluid ounces. A UK (imperial) gallon is exactly 4.54609 liters and holds 160 UK fluid ounces, so it is about 20 percent larger. US and UK pints and fluid ounces differ in the same way.
Every factor is the exact legal definition published by NIST, the US National Institute of Standards and Technology: Special Publication 811 for the inch, foot, mile, pound and temperature formulas, Handbook 44 for gallons, cups and tablespoons, and NIST's binary-prefix page for KiB and MiB. The Definitions tab lists each unit.
Rates and rules change; check the source before you rely on a figure.
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