Miles per hour to Kilometers per hour Converter

The converter above is already set to miles per hour and kilometers 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 60. Decimals and negative numbers are accepted.
2. Check that From shows miles per hour and To shows kilometers 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 mile 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 mile per hour is exactly 1.60934 kilometers per hour, so the formula is kilometers per hour = miles per hour x 1.60934. Going the other way, one kilometer per hour is about 0.621371 miles per hour. One mile per hour is exactly 0.44704 meters per second. One kilometer per hour is 0.2778 meters per second, since 3.6 kilometers per hour make one meter per second.

Worked examples with the same factor:

• 60 miles per hour: 60 x 1.60934 = 96.5606 kilometers per hour
• 150 miles per hour: 150 x 1.60934 = 241.402 kilometers per hour
• 600 miles per hour: 600 x 1.60934 = 965.606 kilometers per hour

Multiply by 1.6: 60 mph is about 96 km/h, exactly 96.56.

To check the converter by hand, take 150 miles per hour and apply the rule once: the result should be 241.402 kilometers per hour. If you go back again with the reverse factor 0.621371 you land on 150 miles 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.

Speed limits, car speedometers, wind speeds and radar readings change between miles per hour and kilometers per hour at borders.

Speed limits are normally posted in whole numbers, so a rounded conversion is fine on the road, but check whether a sign or instrument shows mph or km/h before you convert. Plane and boat speeds in knots are nautical miles per hour, which are longer than land miles.

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

The page keeps no history, so each visit starts again from the defaults, 60 miles 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.