How to convert mph to km/h?

1 mph = 1.60934 km/h; 1 km/h = 0.62137 mph.

One nautical mile per hour (1,852 m/h), used by ships and aircraft.

Mach 1 ≈ 340 m/s = 1,224 km/h at 15°C sea level.

Speed Converter — km/h mph m/s knot ft/s

Example	km/h	mph	m/s
Walking pace	5	3.1	1.4
Cycling	25	15.5	6.9
Highway car	100	62.1	27.8
High-speed train	300	186.4	83.3
Speed of sound (15°C)	1,235	767.3	343.0

Example

km/h

mph

m/s

Walking pace

3.1

1.4

Cycling

15.5

6.9

Highway car

100

62.1

27.8

High-speed train

300

186.4

83.3

Speed of sound (15°C)

1,235

767.3

343.0

Frequently Asked Questions

What is the formula to convert mph to km/h?

1 mph = 1.60934 km/h. Conversely, 1 km/h = 0.62137 mph. For a quick mental estimate, multiply km/h by 0.6 to get approximate mph.

What is a knot?

One knot equals one nautical mile per hour (1,852 m/h). Knots are used by ships and aircraft worldwide. 1 knot ≈ 1.852 km/h ≈ 0.514 m/s.

What is Mach speed?

Mach 1 equals the speed of sound, approximately 340 m/s = 1,224 km/h = 661 knots at 15°C at sea level. Mach varies with altitude and temperature. Supersonic: Mach 1+, Hypersonic: Mach 5+.

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