Miles per Hour to Kilometers per Hour Converter

Miles per hour is used on roads in the United States and the United Kingdom, while kilometers per hour is common in most other countries. One mile is exactly 1.609344 kilometers, so mph converts to km/h by multiplying by 1.609344. The time unit remains one hour, so the same distance factor applies to speed.

1. 1

   Enter a value

   Type a number into the From box. It starts at 1 so you can see the basic ratio straight away. Thousands separators such as 1,250.5 are accepted.

2. 2

   Choose your units

   This page opens with its own units selected. Use either dropdown to pick any other unit in the category, or tap a unit in the all-units list to make it the target.

3. 3

   Read the result

   The answer updates as you type and the matching formula is shown underneath. There is no Convert button to press.

4. 4

   Swap, copy or clear

   Swap reverses the direction, Copy Result copies a line such as 1 km = 0.621371 mi, and Clear empties the input so you can start again.

Input

• Supported
  Whole numbers25
• Supported
  Decimal numbers2.75

  Use a dot as the decimal separator.

• Supported
  Negative numbers-40

  Calculated for every unit. Quantities such as length or weight are normally positive, while temperatures can be negative.

• Supported
  Thousands separators1,250.5

  Commas must group digits in threes. 1,234 is read as one thousand two hundred thirty-four.

• Supported
  Scientific notation1.5e6

  Useful for very large or very small values (1.5e6 = 1,500,000).

• Not supported
  Comma as decimal mark2,5

  Type 2.5 instead.

• Not supported
  Fractions1/2

  Type 0.5 instead.

• Not supported
  Numbers with unit text5 km

  Enter only the number and choose the unit from the dropdown.

Output

Results use US English formatting (1,234.56) and show up to 6 decimal places with trailing zeros removed. Very small results appear in scientific notation, such as 9.0949e-13, instead of rounding to zero.

Units available in this converter

• Meter per Second (m/s)
• Kilometer per Hour (km/h)
• Mile per Hour (mph)
• Foot per Second (ft/s)
• Knot (kn)

Common values for the units currently selected above, in both directions.

Tips

• For a quick estimate, add about 60% to the mph value; multiplying by 1.609344 is more accurate.
• This converts speed only; it does not account for road conditions or a vehicle's speedometer tolerance.

• Mph uses the statute mile and the knot equals one nautical mile per hour.
• Mach number is not supported because it depends on altitude and air temperature.
• Results show up to 6 decimal places. Values are not rounded during calculation, and a non-zero result that would display as 0 is shown in scientific notation.