Speed

Speed Converter

Convert between mph, km/h, m/s, knots, Mach, and more — instantly.

mph
km/h

How to Convert

Formula

Unit Definition

Unit Definition

Conversion Table

Common Values
From To

Convert from Miles per Hour (mph)

mph to km/h mph to knots mph to Mach mph to speed of sound mph to speed of light mph to ft/s mph to km/s mph to m/s mph to cm/s mph to mm/s mph to ft/min mph to m/min

Convert to Kilometers per Hour (km/h)

knots to km/h Mach to km/h speed of sound to km/h speed of light to km/h ft/s to km/h km/s to km/h m/s to km/h cm/s to km/h mph to km/h km/min to km/h yd/s to km/h ft/min to km/h

All Speed Conversions from mph

Speed Units Explained

Miles per Hour (mph)

The most familiar speed unit in the US and UK. One mph = 1.609344 km/h = 0.44704 m/s. A car travelling at 60 mph covers 1 mile every minute. Highway speed limits in the US are typically 65–75 mph.

Kilometers per Hour (km/h)

The standard road speed unit used in most countries. 1 km/h = 0.621371 mph = 0.27778 m/s. European speed limits are typically 50 km/h in cities, 90–130 km/h on motorways.

Meters per Second (m/s)

The SI unit for speed, used in physics and science. A sprinter running 100 m in 10 seconds averages 10 m/s = 36 km/h = 22.4 mph. Wind speed is often given in m/s in meteorology.

Knots (kn)

One knot = one nautical mile per hour = 1.852 km/h = 1.151 mph. Knots are the international standard for maritime and aviation speeds. A cruising airliner typically flies at 450–500 knots.

Mach Number

Mach number is the ratio of an object's speed to the local speed of sound. Mach 1 ≈ 340.29 m/s (1,225 km/h / 761 mph) at sea level, 15°C. Commercial aircraft cruise at ~Mach 0.85; the SR-71 Blackbird reached Mach 3.3.

Speed of Light (c)

The ultimate speed limit in the universe — exactly 299,792,458 m/s (≈ 186,282 miles per second). Light travels from Earth to the Moon in ~1.28 seconds and from the Sun to Earth in ~8.3 minutes.

Quick Reference: Key Conversions

1 mph = 1.60934 km/h 1 km/h = 0.62137 mph 1 m/s = 3.6 km/h 1 km/h = 0.27778 m/s 1 knot = 1.852 km/h 1 knot = 1.15078 mph 1 ft/s = 1.09728 km/h 1 Mach ≈ 1,225 km/h 1 Mach ≈ 761 mph Speed of light ≈ 1.08 × 10⁹ km/h

Frequently Asked Questions

How do you convert km/h to mph?

To convert km/h to mph, multiply by 0.6214. For example, 100 km/h × 0.6214 = 62.14 mph.

What is a knot in speed?

A knot is a unit of speed equal to one nautical mile per hour, approximately 1.852 km/h or 1.151 mph. It is widely used in aviation and maritime navigation.

What is Mach 1 in km/h?

Mach 1 is the speed of sound, approximately 1,235 km/h (767 mph) at sea level in dry air at 20°C. Mach numbers are commonly used in aviation and aerodynamics.

What is 100 mph in km/h?

100 mph equals approximately 160.93 km/h. To convert mph to km/h, multiply by 1.60934.