Speed Converter: km/h, mph, Knots, m/s, Mach
Convert between every speed unit in one tool. Kilometers per hour, miles per hour, meters per second, knots, Mach, and feet per second. Useful for driving abroad, aviation, sailing, physics, athletics, and weather. Any-to-any conversion with a single tap to swap direction.
Convert any speed unit
1 km/h = 0.621371 mph
Popular speed conversions
Quick links to the most-searched conversion directions.
All supported speed units
Every unit in the converter, with its precise definition and common use.
| Unit | Symbol | Definition | Common use |
|---|---|---|---|
| Kilometers per hour | km/h | Distance in km divided by time in hours. | Road speed limits and car speedometers outside the US. |
| Miles per hour | mph | 1 mph = 1.6093 km/h. US and UK road speed unit. | US and UK road, sports radars, weather reports. |
| Meters per second | m/s | SI unit of speed. 1 m/s = 3.6 km/h. | Physics, engineering, athletics (sprint timing). |
| Knots | kn | Nautical miles per hour. 1 knot = 1.852 km/h. | Aviation, sailing, weather wind speeds. |
| Mach | mach | Multiples of the speed of sound (343 m/s at sea level, 20°C). | Supersonic aircraft, rockets, ballistics. |
| Feet per second | ft/s | 1 ft/s = 0.3048 m/s. | US engineering, ballistics, baseball pitch speeds. |
What this converter gives you
All speed units
Road, sea, air, and physics units in one tool. km/h, mph, m/s, knots, Mach, ft/s.
Mach reference
Mach 1 uses the standard sea-level dry-air value of 343 m/s.
Swap in one tap
Reverse direction instantly with the result becoming the new input.
Quick value chips
One-click presets for common speeds.
100% private
Runs in your browser. Nothing sent to a server.
Mobile-friendly
Works on phones, tablets, and desktops.
When you need a speed converter
Driving abroad
Convert your speedometer reading between km/h and mph when you cross borders.
Reading weather and wind
Wind speeds in forecasts can be in km/h, mph, or knots depending on the source.
Aviation and sailing
Pilots and sailors use knots; ground crews and passengers think in km/h or mph.
Physics homework
Convert problem inputs to SI m/s before applying physics formulas.
Athletics and pace
Convert treadmill speed (km/h) to running pace per mile, or vice versa.
Vehicle reviews
Reviews from different countries quote 0-60 mph or 0-100 km/h; the converter lets you compare.
About speed measurement
km/h vs mph
Most of the world uses km/h on speedometers. The US, UK, Liberia, Myanmar, and a handful of other countries use mph. 100 km/h is 62.14 mph; 60 mph is 96.56 km/h. A useful mental rule is 5 mph equals 8 km/h: 25 mph is 40 km/h, 50 mph is 80 km/h, 75 mph is 120 km/h. The calculator gives exact values to 6 significant figures.
Why pilots and sailors use knots
A knot is one nautical mile per hour, and a nautical mile equals one minute of arc along a meridian. This makes navigation calculations cleaner: at 1 knot you cover one minute of latitude per hour. Knots have been the standard at sea for centuries and remain the standard in aviation today. 1 knot equals 1.852 km/h or 1.151 mph.
Meters per second in physics
m/s is the SI unit and the right unit for physics formulas. Energy (E = 1/2 mv²), momentum (p = mv), and forces (F = ma) all expect SI units, so converting km/h to m/s by dividing by 3.6 is often the first step. Athletic sprint times (Usain Bolt's 100m world record averaged about 10.4 m/s) are usually quoted in m/s for the same reason.
The Mach scale
Mach 1 is the speed of sound. At sea level in dry air at 20 degrees Celsius this is 343 m/s, or 1,236 km/h, or 768 mph. Mach 2 is twice the speed of sound. The Concorde cruised at about Mach 2. The X-15 set a record of Mach 6.72 (the highest manned aircraft speed). The speed of sound varies with temperature and altitude, so the Mach number is relative to local conditions.
Speed limits around the world
Typical highway speed limits: Germany Autobahn 130 km/h (recommended, unlimited stretches). France motorway 130 km/h. UK motorway 70 mph (113 km/h). US interstate 65 to 80 mph (105 to 129 km/h). Australia 100 to 110 km/h. Pakistan motorway 120 km/h. India expressway 100 to 120 km/h. The calculator helps you read foreign road signs.
Running and cycling speeds
Average human walking pace is about 5 km/h. A brisk walk is 6 km/h. Running speeds: jogging 8 to 9 km/h, easy run 10 to 11 km/h, marathon (elite) 20 km/h. Cycling: casual 15 to 20 km/h, fit amateur 25 to 30 km/h, professional time-trial 50 km/h+. Tour de France peloton averages around 40 km/h.
Vehicle and aircraft speeds
A Toyota Corolla tops out around 195 km/h. A typical sports car around 270 km/h. The Bugatti Chiron Super Sport 300+ has hit 490 km/h. A 737 cruises at 840 km/h (520 mph, 453 knots). A 747 cruises at 920 km/h. The X-15 hit 7,274 km/h, about Mach 6.7. The International Space Station orbits at 7.66 km/s (27,600 km/h).
Mental conversion shortcuts
For km/h to mph: divide by 1.6, or multiply by 0.6, or subtract 40 percent. For mph to km/h: multiply by 1.6, or add 60 percent. The Fibonacci sequence helps too: consecutive Fibonacci numbers (3, 5), (5, 8), (8, 13), (13, 21) are close to the mile-to-kilometer ratio, so 13 km is about 8 miles. Use the calculator for exact values.
Wind speed scales
The Beaufort scale measures wind force: 0 is calm (under 1 km/h), 6 is strong breeze (39 to 49 km/h), 10 is storm (89 to 102 km/h), and 12 is hurricane (over 118 km/h). Hurricane categories (Saffir-Simpson) start at 119 km/h for Category 1 and go up to 252 km/h+ for Category 5. Knots are also used for wind speed in marine forecasts.
Multiply km/h by 0.6214 to get mph. So 100 km/h is 62.14 mph. For a rough mental estimate, multiply km/h by 0.6 (slight under-estimate). The calculator gives the exact figure with one tap.
Multiply mph by 1.6093 to get km/h. So 60 mph is 96.56 km/h. For mental math, multiply mph by 1.6. The 5-to-8 shortcut works too: 5 mph is about 8 km/h.
A knot is one nautical mile per hour, equal to 1.852 km/h or 1.151 mph. It is the standard speed unit at sea and in aviation. So an aircraft cruising at 500 knots is doing about 926 km/h or 575 mph.
Mach 1 is the speed of sound, approximately 343 m/s or 1,236 km/h (768 mph) in dry air at 20 degrees Celsius and sea level. The speed of sound varies with temperature and altitude, so Mach numbers are relative to local conditions. Supersonic flight starts above Mach 1.
km/h, mph, m/s, knots, Mach, and ft/s. Any-to-any conversion is supported. The speed of sound (Mach) uses the standard sea-level dry-air value of 343 m/s.
An MLB fastball typically runs 90 to 100 mph, which is 145 to 161 km/h. Aroldis Chapman holds the modern MLB record at 105.8 mph (170.3 km/h). Cricket fast bowlers typically pitch at 140 to 155 km/h (87 to 96 mph).
The current land speed record is 1,228 km/h (763 mph), set by Andy Green in 1997 in the ThrustSSC. Both km/h and mph are used in motorsport, so a converter is useful for comparing international race speeds.
Average walking pace is about 5 km/h (3.1 mph). A brisk walk is around 6 to 7 km/h (3.7 to 4.3 mph). A fast walk is about 8 km/h (5 mph). Race walkers compete at 12 to 14 km/h (7.5 to 8.7 mph), which is faster than many people can run.
Jogging is generally considered below 9 km/h (5.6 mph). Easy running is around 9 to 11 km/h (5.6 to 6.8 mph). Marathon pace for amateur runners is 10 to 13 km/h. Elite marathon pace is around 20 km/h (12.4 mph).
In Europe, typically 100 to 130 km/h (62 to 81 mph). In the US, 65 to 75 mph (105 to 121 km/h) on most interstates. In Australia, 100 to 110 km/h. The German Autobahn has unlimited stretches but a recommended 130 km/h. The UK uses mph with 70 mph (113 km/h) standard.
Cruise speed for a Boeing 737 or Airbus A320 is about 840 km/h (520 mph or 453 knots). A 747 cruises at about 920 km/h (570 mph or 495 knots). These are airspeeds; ground speed varies with wind.
Yes. The converter uses double-precision arithmetic and shows results to 6 significant figures. It can handle anything from a snail (0.013 km/h) to the speed of light (1.08 billion km/h) without precision issues. For everyday speeds the precision is far beyond what any speedometer shows.
Yes. All values stay in your browser. Nothing is sent to a server, logged, or shared. You can use the calculator offline once the page has loaded.