What is mile per hour?

Mile per hour is a unit of speed equal to one mile travelled in one hour. It is the standard unit for road speeds, vehicle performance ratings, and weather reports in the United States and United Kingdom.

Real-world uses

Miles per hour is the standard speed unit for road traffic in the United States, the United Kingdom, and a few other countries. Baseball pitching speed, hurricane wind categories (Saffir-Simpson scale), and NASCAR race speeds are quoted in mph.

History

Miles per hour became the standard speed expression in English-speaking countries with the advent of railways and later automobiles. The first US speed limit (8 mph in New York City, 1901) and British speed cameras use mph as the legal standard.

Common mistakes

Assuming mph-to-km/h conversion is a simple ×1.5—the actual factor is 1.609. Also, forgetting that UK and US speed limits both use mph, which can mislead visitors from metric countries into driving too fast or too slow.

What is metre per second?

Metre per second is the SI unit of speed. It is used in physics, engineering, and scientific contexts to express velocity, and serves as the reference unit for all speed calculations in this converter.

Real-world uses

Metres per second is the SI unit of speed used in physics, engineering, and scientific research. Wind speed in meteorological data, projectile velocities, and fluid flow rates are expressed in m/s. The speed of sound at sea level is approximately 343 m/s.

History

As an SI derived unit, metres per second became the standard scientific speed unit with the adoption of the SI system in 1960. It naturally combines the base units of length (metre) and time (second).

Common mistakes

Forgetting to convert from km/h—divide by 3.6, not by 3.0 or 60. Also, confusing velocity (vector with direction) with speed (scalar magnitude), both expressed in m/s but with different physical meanings.

When is this conversion used?

Converting between mile per hour and metre per second is common when working across metric and imperial systems, such as international trade, travel between countries with different measurement standards, or following instructions from a different region. Speed limits, vehicle speedometers, and weather reports for wind speeds use different units depending on the country, making km/h to mph conversion one of the most practical speed conversions.

Worked examples

1 mile per hour = 0.44704 metre per second

1 metre per second = 1 metre per second

How to convert mile per hour to metre per second

To convert mile per hour to metre per second, multiply the value by 0.44704.

To convert metre per second back to mile per hour, multiply by 2.23693629.

Measurement standards

The SI unit of speed is metres per second (m/s), a derived unit requiring no independent definition. The knot is defined as exactly one nautical mile (1,852 metres) per hour and is sanctioned for maritime and aeronautical navigation by the International Civil Aviation Organization.

Did you know?

The fastest human-made object is the Parker Solar Probe, which reached 635,266 km/h (about 176 km/s) in 2024 during a close pass of the Sun — fast enough to travel from New York to Tokyo in under a minute.

Quick reference: mile per hour to metre per second

mile per hour	metre per second
0.1	0.044704
0.5	0.22352
1	0.44704
2	0.89408
5	2.2352
10	4.4704
25	11.176
50	22.352
100	44.704
250	111.76
500	223.52
1,000	447.04

Common values

	mile per hour	metre per second
Walking speed	3.13171081 mile per hour	1.4 metre per second
City speed limit	31.09341446 mile per hour	13.9 metre per second
Highway driving	70.01610594 mile per hour	31.3 metre per second
Commercial aircraft	559.23407301 mile per hour	250 metre per second
Speed of sound (sea level)	761.20705082 mile per hour	340.29 metre per second

Available Speed units

More mile per hour conversions

Assumption: Mach uses an approximate sea-level reference (about 340.29 m/s).