Introduction
This km to miles calculator changes kilometers into miles in one step. Type a number, and the answer shows up right away. You can also go the other way and change miles into kilometers by tapping the Swap button.
The math is simple: 1 kilometer = 0.62137119223733 miles, and 1 mile = 1.609344 kilometers. The tool uses these exact numbers, so your answer is always correct.
You can pick how many decimal places you want, from 0 to 4, or choose "Full" to see every digit. You can also pick American spelling (kilometers) or British spelling (kilometres). A step-by-step section shows how the answer was found, and the tables below give quick answers for common distances.
This helps with road signs, running races like a 5K or 10K, car trips in other countries, and school work.
How to use our Km to Miles Calculator
Type a distance in kilometers, and the calculator shows the same distance in miles right away. You also get a step-by-step solution, a conversion line chart, and quick reference tables.
Decimal Places: Pick how many numbers you want after the decimal point. Choose 0, 1, 2, 3, or 4, or pick "Full" to see the exact answer with no rounding.
Spelling: Choose "American (Kilometers)" or "British (Kilometres)". This only changes how the word is spelled, not the math.
Value in kilometers (From): Type your km value here. Use digits and one decimal point, like 12.5. The miles box fills in as you type.
Value in miles (To): You can type here instead. Enter a mile value and the kilometers box updates. This turns it into a miles to km converter.
Swap: Click this to flip the direction. It switches the boxes between kilometers to miles and miles to kilometers.
Calculate: Click this to run the conversion. You can also just press Enter in either box.
Clear: Click this to empty both boxes and start over.
Copy: Click the copy button next to a box to save that number to your clipboard.
Kilometers to Miles: What It Means
A kilometer and a mile are both ways to measure distance. Most of the world uses kilometers. The United States and the United Kingdom still use miles on road signs and speed limits. So when you travel, read a map, or run a race, you may need to switch between them.
The Conversion Formula
A mile is longer than a kilometer. In fact, 1 mile equals exactly 1.609344 kilometers. That means 1 kilometer equals about 0.621371 miles.
- Kilometers to miles: multiply by 0.621371
- Miles to kilometers: multiply by 1.609344
Example: 10 km × 0.621371 = 6.21 miles. Going the other way, 10 miles × 1.609344 = 16.09 km.
A Quick Trick in Your Head
You do not always need exact math. A kilometer is a little more than half a mile. So cut the kilometers in half, then add a small bit back. For 20 km: half is 10, add about 2, and you get roughly 12 miles. The real answer is 12.43 miles, so the trick is close enough for everyday use.
Where You Will Use It
Runners see this a lot. A 5K race is 3.11 miles. A 10K is 6.21 miles. A marathon is 42.195 km, or 26.219 miles.
Drivers use it too. A 100 km/h speed limit is about 62 mph. Flight distances, hiking trails, and bike rides all use one unit or the other, so converting helps you plan time and fuel.
Why the Two Units Exist
The kilometer comes from the metric system, built on the meter. It is 1,000 meters. The mile is much older and comes from Roman times, when a mile was 1,000 paces. Today the mile is set at 5,280 feet, and its link to the meter is fixed by law, which is why 1.609344 is an exact number and not a rounded guess. The same kind of fixed factor shows up in other conversions, like pounds to kilograms, liters to gallons, and Celsius to Fahrenheit.
Spelling Note
You may see "kilometre" instead of "kilometer." Both are correct. "Kilometer" is American spelling and "kilometre" is British spelling. The distance is the same either way.