Speed Converter
Select the source unit, enter the speed and instantly get all conversions.
m/s
mph
knots
ft/s
Speed Converter – Convert mph, km/h, m/s, Knots, and ft/s
The speed converter instantly translates between all major speed units. Enter a value in any unit and see the equivalent in miles per hour (mph), kilometers per hour (km/h), meters per second (m/s), knots (kn), and feet per second (ft/s). Essential for travel, science, aviation, and everyday conversions.
Speed Unit Conversion Factors
| Unit | Abbreviation | Relative to 1 m/s | Used In |
|---|---|---|---|
| Kilometer per hour | km/h | 1 km/h = 0.2778 m/s | Most countries (speed limits, weather) |
| Mile per hour | mph | 1 mph = 0.4470 m/s | US, UK (roads, weather) |
| Meter per second | m/s | SI base unit | Science, engineering, physics |
| Knot | kn | 1 kn = 0.5144 m/s | Aviation, maritime navigation |
| Foot per second | ft/s | 1 ft/s = 0.3048 m/s | US engineering, ballistics |
Quick Conversion Reference
| From → To | Multiply By | Example |
|---|---|---|
| mph → km/h | 1.60934 | 60 mph = 96.6 km/h |
| km/h → mph | 0.62137 | 100 km/h = 62.1 mph |
| m/s → mph | 2.23694 | 10 m/s = 22.4 mph |
| mph → m/s | 0.44704 | 60 mph = 26.8 m/s |
| knots → mph | 1.15078 | 100 kn = 115.1 mph |
| mph → knots | 0.86898 | 100 mph = 86.9 kn |
| km/h → m/s | 0.27778 | 36 km/h = 10 m/s |
Common Speed References
| Activity / Object | mph | km/h | m/s |
|---|---|---|---|
| Walking | 3.1 | 5 | 1.4 |
| Jogging | 6.2 | 10 | 2.8 |
| Cycling (casual) | 12 | 19 | 5.3 |
| US residential speed limit | 25 | 40 | 11.2 |
| US highway speed limit | 65 | 105 | 29.1 |
| Fastest human (Usain Bolt) | 27.3 | 44.0 | 12.2 |
| Commercial airplane | 575 | 925 | 257 |
| Speed of sound (sea level) | 767 | 1,235 | 343 |
Why Different Speed Units Exist
- mph — Used in the United States, United Kingdom, and a few other countries that retained Imperial measurements for road speed. All US speed limits and car speedometers display mph
- km/h — The standard in most of the world. Used for road signs, weather reports, and everyday purposes across Europe, Asia, South America, and Africa
- m/s — The SI base unit for speed. Used universally in science, physics, and engineering. Wind speeds in weather forecasts are sometimes given in m/s
- Knots — The nautical mile per hour. One knot = one nautical mile (1.852 km) per hour. Used universally in aviation and maritime navigation because nautical miles relate directly to degrees of latitude
Understanding Knots in Aviation and Sailing
The knot is the international standard for aviation and marine speed. Pilots report airspeed, ground speed, and wind speed in knots. Air traffic control, weather reports (METARs and TAFs), and nautical charts all use knots.
Why? One nautical mile equals one minute of latitude, making navigation calculations simpler. At 60 knots, a vessel covers 1 degree of latitude per hour.
The Mach Number
For very high speeds, the Mach number expresses speed relative to the speed of sound:
- Mach 1 = speed of sound ≈ 767 mph (1,235 km/h) at sea level
- Mach 2 = twice the speed of sound ≈ 1,534 mph
- Commercial jets fly at about Mach 0.80–0.85 (500–575 mph)
- The SR-71 Blackbird reached Mach 3.3 (2,200 mph)
- The Space Shuttle re-entered the atmosphere at Mach 25 (17,500 mph)
Frequently Asked Questions
How do I convert mph to km/h?
Multiply mph by 1.60934. For example, 60 mph × 1.60934 = 96.56 km/h. For a quick estimate, multiply by 1.6 — so 60 mph ≈ 96 km/h.
How fast is 100 km/h in mph?
100 km/h equals 62.14 mph. This is a common highway speed limit in countries using the metric system, roughly equivalent to a 60 mph US highway speed limit.
What is the difference between speed and velocity?
Speed is a scalar quantity — just how fast something moves, regardless of direction. Velocity is a vector quantity — speed plus direction. For everyday unit conversions, speed is the relevant measurement.
How do I convert m/s to mph?
Multiply m/s by 2.23694. For example, 10 m/s × 2.23694 = 22.37 mph. This is useful for converting scientific measurements to everyday units.
What is the speed of light in mph?
The speed of light is approximately 670,616,629 mph (299,792,458 m/s or about 1.08 billion km/h). It is the universal speed limit — nothing with mass can reach or exceed it.
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