Converter category
Speed Converter
Convert between meters per second, km/h, mph, feet per second, knots, Mach, speed of light, and various other speed units.
Universal Speed Converter
About speed conversions
Speed conversions are used when driving, flying, running, cycling, or analyzing vehicles and machinery. Our speed converter covers everyday units such as kilometers per hour and miles per hour, scientific units like meters per second, and specialized units including feet per second, knots, and nautical miles per hour. It also includes extreme values like the speed of light and Mach numbers. Whether you are checking a speed limit, comparing vehicle performance, or working on physics problems, you can convert quickly and accurately.
Most popular speed conversions
Available units
Popular speed conversions (1124 total)
Unit definitions
Meter per Second (m/s)
A meter per second is the SI unit of speed. 1 m/s equals approximately 3.28 feet per second.
Origin: Derived from the meter (SI base unit) and second (SI base unit).
Current use: Scientific measurements, Wind speed, Vehicle speeds
Kilometer per Hour (km/h)
Kilometers per hour is the standard unit of speed in most countries. 1 km/h equals approximately 0.62 mph.
Origin: Standard speed limit unit in most countries worldwide.
Current use: Road speed limits, Running pace, Cycling speed
Mile per Hour (mph)
Miles per hour is the standard speed unit in the US and UK. 1 mph equals 1.609 km/h.
Origin: Used in the US and UK for road speeds and vehicle performance.
Current use: US/UK speed limits, Vehicle speeds, Wind speed (US)
Foot per Second (ft/s)
Feet per second is used in engineering and physics. 1 ft/s equals 0.3048 m/s.
Origin: Part of the Imperial system of measurement.
Current use: Physics calculations, Fluid dynamics, Projectile motion
Knot (kn)
A knot is one nautical mile per hour, used in maritime and aviation navigation. 1 knot ≈ 1.15 mph.
Origin: Derived from the old method of measuring ship speed using a knotted rope thrown overboard.
Current use: Marine navigation, Aviation, Weather reporting
Mach (Mach)
Mach 1 is the speed of sound. Mach number is the ratio of an object's speed to the speed of sound in the surrounding medium.
Origin: Named after Ernst Mach, an Austrian physicist who studied supersonic motion.
Current use: Aviation, Rocketry, Supersonic flight
Speed of Light (c)
Light speed in vacuum = 299,792,458 m/s. Universal constant.
Origin: Einstein's constant for relativity.
Current use: Physics, Astronomy, Relativity
Mile per Hour Meter (mph·m)
US speed for slow processes.
Origin: Slow speed measurement.
Current use: Slow conveyors, US industry, Machinery
Mile per Minute (mpm)
High speed - 60 mph.
Origin: Vehicle speed.
Current use: Aircraft, Racing, High speed trains
Kilometer per Minute (kmpm)
Metric high speed = 60 km/h.
Origin: Metric speed.
Current use: European rail, Trams, Conveyors
Kilometer per Second (km/s)
Very high speed - rocket velocity.
Origin: Space physics.
Current use: Spacecraft, Asteroids, Physics
Centimeter per Hour (cm/h)
Very slow speed - glaciers, geological.
Origin: Scientific measurement.
Current use: Glaciers, Geology, Scientific research
Centimeter per Minute (cm/min)
Slow process speed.
Origin: Industrial processes.
Current use: Slow conveyors, Drying, Heating
Centimeter per Second (cm/s)
Small object speed.
Origin: Physics labs.
Current use: Walking speed, Small objects, Labs
Millimeter per Hour (mm/h)
Extremely slow - groundwater flow.
Origin: Hydrology.
Current use: Groundwater, Pollution, Environmental
Millimeter per Minute (mm/min)
Very slow creep.
Origin: Materials testing.
Current use: Materials testing, Creep, Long-term studies
Millimeter per Second (mm/s)
Fine precision speed.
Origin: Engineering.
Current use: Robotics, Precision machinery, Labs
Foot per Hour (ft/h)
Very slow US speed.
Origin: Slow processes.
Current use: US slow processes, Thermal expansion, Geology
Foot per Minute (ft/min)
Slow US conveyor speed.
Origin: US industry.
Current use: US conveyors, HVAC, Ventilation
Yard per Hour (yd/h)
Very slow Imperial speed.
Origin: Slow processes.
Current use: Slow moving, Textiles, Coatings
Yard per Minute (yd/min)
Moderate Imperial speed.
Origin: US industry.
Current use: US manufacturing, Textile, Conveyors
Yard per Second (yd/s)
Fast Imperial speed.
Origin: Sports.
Current use: Baseball, American football, Track
Mile per Minute (mi/min)
Very high speed - aircraft.
Origin: Aviation.
Current use: Aircraft, Rockets, Space
Mile per Second (mi/s)
Extreme speed - orbital.
Origin: Space physics.
Current use: Orbital velocity, Spacecraft, Physics
UK Knot (kn UK)
UK nautical mile per hour.
Origin: British maritime standard.
Current use: UK shipping, British navy, Historical
Speed of Light in Vacuum (c)
Light speed in vacuum = 299,792,458 m/s.
Origin: Einstein's constant.
Current use: Physics, Astronomy, Relativity
First Cosmic Velocity (v1)
Orbital velocity for Earth orbit.
Origin: Space physics.
Current use: Satellites, Spacecraft, Orbital mechanics
Second Cosmic Velocity (v2)
Escape from Earth = 11.2 km/s.
Origin: Space physics.
Current use: Spacecraft, Moon missions, Interplanetary
Third Cosmic Velocity (v3)
Escape solar system = 16.7 km/s.
Origin: Space physics.
Current use: Voyager missions, Deep space, Interstellar
Earth's Orbital Velocity (v_earth)
Earth orbits Sun at ~30 km/s.
Origin: Astronomy.
Current use: Astronomy, Calendars, Orbital mechanics
Speed of Sound in Water (v_sound_water)
Sound in fresh water at 25°C.
Origin: Underwater acoustics.
Current use: Sonar, Marine biology, Submarines
Speed of Sound in Sea Water (v_sound_sea)
Sound in seawater ~1540 m/s.
Origin: Naval acoustics.
Current use: Naval sonar, Oceanography, Fishing
Mach at 20°C (M_20C)
Speed of sound at 20°C = 343 m/s.
Origin: Aeronautics.
Current use: Aviation, Aircraft, Aerodynamics
Mach (SI Standard) (M_SI)
Approximate speed of sound.
Origin: Aviation standard.
Current use: Aircraft speed, Wind tunnels, Aerospace
Common uses for speed conversions
Speed conversions are used for driving, aviation, maritime navigation, athletics, cycling, physics, and vehicle specifications.
Frequently asked questions about speed
How do you convert km/h to mph?+
Multiply km/h by 0.621371. For example, 100 km/h is about 62.14 mph.
What is the difference between mph and knots?+
Miles per hour measure land speed. Knots measure nautical speed: 1 knot equals 1 nautical mile per hour, or about 1.151 mph.
Which speed units does this converter support?+
It supports metric, Imperial, nautical, scientific, and extreme speed units — over 15 in total.