## Definitions

### Kilometers per hour

Kilometer per hour is a unit of speed that measures the number of kilometers an object travels within an hour. Kilometer is defined as one thousand meters, the base length unit in SI system of units. Typically, kilometer per hour is denoted as a ratio km/h. However, it also appears as an abbreviation (kmph, kph), particularly on labels or road signs.

Besides km/h, another widespread speed unit is the meters per second [m/s] and its fractions or multiples, defined through the decimal SI prefixes, as shown in the table:

Unit | Symbol | [km/h] |
---|---|---|

Nanometer per second | nm/s | \(3.6 \cdot 10^{-9}\) |

Micrometer per second | μm/s | \(3.6\cdot 10^{-6}\) |

Millimeter per second | mm/s | \(0.0036\) |

Centimeter per second | cm/s | \(0.036\) |

Meter per second | m/s | \(3.6\) |

Kilometer per second | km/s | \(3600\) |

Megameter per second | Mm/s | \(3.6\cdot10^6\) |

Gigameter per second | Gm/s | \(3.6\cdot10^9\) |

### Miles per hour

Mile per hour is a unit of speed defined in the Imperial and US customary system of units. It measures the number of miles an object travels within an hour. International mile [mi] is a unit of length for the US customary system of units, equal to 5280 feet and precisely defined as 1609.344 meters. The symbol most commonly used on signs and labels is the abbreviation mph, however in science and engineering contexts, mi/h may be more convenient for unit arithmetic.

Besides miles per second, other speed units native to the Imperial/US customary systems, are also in common use. Their relationship, relative to the mile per hour, is shown in the table:

Unit | Symbol | [mph] |
---|---|---|

Inch per second | ips | \(\frac{3600}{63,360}=\frac{5}{88}\) |

Inch per minute | ipm | \(\frac{60}{63,360}=\frac{1}{1056}\) |

Inch per hour | iph | \(\frac{1}{63,360}\) |

Feet per second | fps | \(\frac{3600}{5280}=\frac{15}{22}=\approx 0.681818\) |

Feet per minute | fpm | \(\frac{60}{5280}=\frac{1}{88}\) |

Feet per hour | fph | \(\frac{1}{5280}\) |

Miles per second | mps | \(3600\) |

Miles per minute | mpm | \(60\) |

### How to convert miles per hour to kilometers per hour

- Multiply speed in mph with 1.609344
- The result is the speed in kilometers per hour

For example 60 mph is 60x1.609344≈ 96.6 km/h

### How to convert kilometers per hour to miles per hour

- Divide speed in km/h by 1.609344
- The result is the speed in mph

For example 110 km/h is 110/1.609344≈ 68.4 mph

### Conversion table from [km/h] to [mph]

In the following table some typical speeds in kilometers per hour are converted to miles per hour:

[km/h] | [mph] |
---|---|

1 | |

5 | |

10 | |

20 | |

30 | |

40 | |

50 | |

60 | |

70 | |

80 | |

90 | |

100 | |

110 | |

120 | |

130 | |

140 | |

150 | |

160 | |

180 | |

200 | |

300 |

### Conversion table from [mph] to [km/h]

In the following table some typical speeds in miles per hour are converted to kilometers per hour:

[mph] | [km/h] |
---|---|

1 | |

2 | |

5 | |

10 | |

15 | |

20 | |

25 | |

30 | |

35 | |

40 | |

45 | |

50 | |

55 | |

60 | |

65 | |

70 | |

80 | |

90 | |

100 | |

120 | |

200 |