Kilometers per hour to Miles per hour Converter

The converter above is already set to kilometers per hour and miles per hour, so you only need to enter your number. The result updates as you type, and nothing is sent anywhere.

1. Type your value in the Value box, for example 100. Decimals and negative numbers are accepted.
2. Check that From shows kilometers per hour and To shows miles per hour. Both menus can be changed if you need a different pair.
3. Read the answer in the large result box. The note under it shows the exact factor used for one kilometer per hour.
4. Press Copy result to put the answer on your clipboard, or Swap units to convert in the opposite direction.
5. Look at In every unit on the right to see the same amount in all the other speed units.

One kilometer per hour is about 0.621371 miles per hour, so the formula is miles per hour = kilometers per hour x 0.621371. Going the other way, one mile per hour is exactly 1.60934 kilometers per hour. One kilometer per hour is 0.2778 meters per second, since 3.6 kilometers per hour make one meter per second. One mile per hour is exactly 0.44704 meters per second.

Worked examples with the same factor:

• 100 kilometers per hour: 100 x 0.621371 = 62.1371 miles per hour
• 250 kilometers per hour: 250 x 0.621371 = 155.343 miles per hour
• 1,000 kilometers per hour: 1,000 x 0.621371 = 621.371 miles per hour

Multiply by 0.62: 100 km/h is about 62 mph, exactly 62.14.

To check the converter by hand, take 250 kilometers per hour and apply the rule once: the result should be 155.343 miles per hour. If you go back again with the reverse factor 1.60934 you land on 250 kilometers per hour, which confirms that the two directions agree. Rounding the factor to fewer digits for mental math gives a result that is close but not identical, so use the tool when the last digits matter.

These reference values come from the same factor the converter uses, so they match what you see above. Use the table for common amounts, and the converter for anything else.

Speed is distance divided by time, so a speed conversion changes both a length unit and a time unit at once. Miles per hour and kilometers per hour differ only in the length part, while meters per second also changes the time part, which is why the factor of 3.6 appears between them. Knots add a third system based on the nautical mile, which is tied to one minute of latitude.

Use the table as a sanity check rather than a substitute for the converter. Highway speeds, bicycle speeds and walking speeds are good reference points: a brisk walk is about 5 km/h or 3 mph, a bicycle commuter about 20 km/h or 12 mph. If your result is far from the speed you expected for the situation, check which unit you typed.

European speed limits and speedometers, cycling speeds and running paces are in km/h, while road signs in the United States and United Kingdom use mph.

Remember that a speed is a ratio of distance to time. When you convert a pace such as minutes per kilometer, you cannot use a speed factor directly; convert to a speed first, then back.

Related pages: Miles per hour to Kilometers per hour Converter for the reverse direction, and the knots to miles per hour and meters per second to kilometers per hour pages. For other speed units use the speed converter.

The page keeps no history, so each visit starts again from the defaults, 100 kilometers per hour. Your numbers are processed by JavaScript in your own browser and are never sent to a server, which makes the converter safe for private figures such as medical, financial or work measurements.