To convert m/s to km/h (also written as kph), multiply by 3.6. The factor comes from unit definitions: 3,600 seconds per hour ÷ 1,000 meters per kilometer = 3.6. So 10 m/s = 36 km/h. For the reverse, divide km/h by 3.6.
- Exact factor: km/h (kph) = m/s × 3.6 (derived from SI definitions, no rounding).
- 100 km/h = 27.778 m/s - the value to use in physics calculations at motorway speed.
- Physics uses m/s; road signs use km/h or kph - this is the most common unit bridge in science education.
- Wind speeds in meteorology and physics are always m/s; forecasts for the public use km/h, kph, or mph.
How to use this converter
Type a speed value into any of the five fields - m/s, km/h (kph), mph, ft/s, or knots - and all the other fields update instantly. There's no submit button. You can start from any unit and read off the rest. For example, type 100 in the km/h field and you'll immediately see 27.78 m/s, 62.14 mph, 91.13 ft/s, and 53.99 knots.
How do you convert m/s to km/h?
Multiply meters per second by 3.6. The factor is exact and derived directly from the SI unit system: 1 hour = 3,600 seconds; 1 kilometer = 1,000 meters. So 1 m/s means 1 meter travelled in 1 second. In one hour (3,600 seconds) that's 3,600 meters = 3.6 km.
This is why the factor is always exactly 3.6, with no approximation. NIST Special Publication 811 (Appendix B.8) lists the official factors: 1 km/h = 2.777778 × 10⁻¹ m/s, confirming the 3.6 factor is exact. m/s is the SI coherent derived unit for speed, as defined by the International Bureau of Weights and Measures (BIPM).
$$\text{km/h} = \text{m/s} \times 3.6$$
Worked examples: 5 m/s = 18 km/h. 27.78 m/s = 100 km/h (exactly). 340 m/s = 1,224 km/h (speed of sound at sea level, 15°C).
How do you convert km/h to m/s?
Divide km/h by 3.6. Equivalently, multiply by 0.27778 (the reciprocal of 3.6). This is the conversion used in every physics problem that starts with a road speed: a car travelling at 90 km/h is moving at 90 ÷ 3.6 = 25 m/s. For the full multi-unit speed converter, use the hub which handles m/s, km/h, mph, and knots together.
$$\text{m/s} = \frac{\text{km/h}}{3.6}$$
Worked examples: 36 km/h = 10 m/s. 72 km/h = 20 m/s. 120 km/h = 33.33 m/s.
How to convert m/s to mph, ft/s, and knots
The converter handles all five common speed units from a single input. Each conversion factor is exact or derived from exact SI definitions. Here are the three additional conversions beyond km/h:
m/s to mph - multiply by 2.23694. One meter per second equals 2.23694 miles per hour. The factor derives from the exact definition of the international mile (1,609.344 m) and seconds-to-hours conversion. Example: 10 m/s = 22.37 mph.
$$\text{mph} = \text{m/s} \times 2.23694$$
m/s to ft/s - multiply by 3.28084. One meter equals exactly 3.28084 feet (derived from the international foot = 0.3048 m). Example: 10 m/s = 32.81 ft/s. This conversion appears in US engineering, ballistics, and HVAC calculations.
$$\text{ft/s} = \text{m/s} \times 3.28084$$
m/s to knots - multiply by 1.94384. One knot equals one nautical mile per hour; NOAA defines the nautical mile as exactly 1,852 m, officially standardized in 1929. So 1 m/s = 3,600 ÷ 1,852 = 1.94384 knots. Example: 10 m/s = 19.44 knots. Used in meteorology buoy data and marine forecasting.
$$\text{kn} = \text{m/s} \times 1.94384$$
Speed reference table: m/s, km/h, mph, ft/s, knots
Key speed values across all five units with real-world contexts. All values are calculated from m/s using exact conversion factors.
| m/s | km/h | mph | ft/s | knots | Context |
|---|---|---|---|---|---|
| 0.5 | 1.8 | 1.1 | 1.6 | 1.0 | Slow walking |
| 1.4 | 5.0 | 3.1 | 4.6 | 2.7 | Normal walking pace |
| 3 | 10.8 | 6.7 | 9.8 | 5.8 | Jogging |
| 5 | 18 | 11.2 | 16.4 | 9.7 | Fast cycling |
| 10 | 36 | 22.4 | 32.8 | 19.4 | Sprinting / Beaufort Force 5 wind |
| 12.4 | 44.6 | 27.7 | 40.7 | 24.1 | Usain Bolt peak speed (100m record) |
| 17 | 61.2 | 38.0 | 55.8 | 33.0 | Beaufort Force 8 (gale) |
| 27.78 | 100 | 62.1 | 91.1 | 54.0 | Motorway speed (EU limit) |
| 33.33 | 120 | 74.6 | 109.4 | 64.8 | Common autobahn speed |
| 83.33 | 300 | 186.4 | 273.4 | 161.9 | High-speed train (TGV Duplex) |
| 340 | 1,224 | 760.7 | 1,115.5 | 661.0 | Speed of sound (sea level, 15°C) |
When do you need to convert m/s to km/h?
Physics and engineering always work in m/s because it's the SI base unit - every equation involving speed, force, energy, or momentum uses m/s directly. Road speeds, vehicle specs, and weather reports for the public use km/h (or mph in the US and UK). This gap creates constant conversion needs in education, sports science, and meteorology.
Common situations:
- Physics homework - textbook problems give car speeds in km/h; kinetic energy and braking distance equations need m/s. Divide by 3.6 before calculating.
- Wind speed - meteorological data from weather stations comes in m/s; public forecasts use km/h (kph). A 10 m/s wind = 36 km/h = 22.4 mph, which is Beaufort Force 5 (fresh breeze) per the NOAA National Weather Service scale.
- Sports science - GPS trackers and speed guns give athlete speeds in m/s; coaches and media report in km/h or mph. Usain Bolt's peak 12.4 m/s = 44.6 km/h = 27.7 mph.
- US engineering and aviation - American structural and mechanical specs use ft/s; aviation uses knots. Converting from m/s lets you work across both systems at once.
- Marine meteorology - offshore weather buoys report wind in m/s; sailors need knots. 17 m/s (gale-force wind) = 33 knots (Beaufort Force 8).
- Fluid dynamics and aerodynamics - equations use m/s; comparing to vehicle speed limits or aircraft airspeeds requires km/h or knots simultaneously.
FAQs about m/s and km/h conversion
How do you convert m/s to km/h?
Multiply m/s by 3.6. This factor is exact: 3,600 seconds per hour ÷ 1,000 meters per kilometer = 3.6. No rounding is involved. Examples: 5 m/s = 18 km/h; 27.78 m/s = 100 km/h; 340 m/s (speed of sound) = 1,224 km/h.
How many m/s is 100 km/h?
100 km/h = 27.778 m/s (100 ÷ 3.6 = 27.7̄). This recurring decimal is exact: 27 and 7/9 m/s. In physics calculations involving a 100 km/h car, use 27.78 m/s for four significant figures or 250/9 m/s for exact arithmetic.
Why does physics use m/s instead of km/h?
m/s is the SI (International System) base unit. All other SI quantities - force in newtons, energy in joules, momentum in kg·m/s - are defined using meters and seconds. Using km/h in physics equations introduces a factor of 3.6 (or 1/3.6) into every calculation, which is error-prone and non-standard.
How fast is 10 m/s in km/h?
10 m/s = 36 km/h (22.4 mph). This is roughly the sprint speed of a fast human or a strong cyclist. Usain Bolt averaged 10.44 m/s over his 9.58-second 100m world record. Wind at 10 m/s is a fresh breeze (Beaufort Force 5) - enough to cause small trees to sway and raise whitecaps on lakes.
What is wind speed of 10 m/s in km/h?
10 m/s = 36 km/h (22.4 mph, 19.4 knots). Weather agencies report wind in m/s in scientific data and in km/h or mph in public forecasts. Per the NOAA NWS Beaufort Wind Scale, 10 m/s is approximately Force 5 (fresh breeze). Beaufort Force 8 (gale) starts at about 17.2 m/s (61.9 km/h, 38 mph, 33 knots).
How do you convert m/s to mph?
Multiply m/s by 2.23694. This factor comes from the exact definition of the international mile (1,609.344 m) divided by 1,000 m/km, divided by 3,600 s/h: 1,609.344 ÷ 1,000 ÷ 3,600 = 0.44704, then its reciprocal 1 ÷ 0.44704 = 2.23694. Example: 10 m/s = 22.37 mph.
How do you convert m/s to ft/s?
Multiply m/s by 3.28084. The international foot is defined as exactly 0.3048 m, so 1 m = 1 ÷ 0.3048 = 3.28084 ft. The conversion from m/s to ft/s is therefore always exactly 3.28084, with no time component needed since both are "per second." Example: 27.78 m/s = 91.13 ft/s.
How do you convert m/s to knots?
Multiply m/s by 1.94384. One knot is one nautical mile per hour, and NOAA defines the nautical mile as exactly 1,852 m. So 1 m/s = 3,600 s/h ÷ 1,852 m/nmi = 1.94384 knots. Example: 10 m/s = 19.44 knots. This is the conversion used when reading data from offshore weather buoys.
What is the difference between km/h, kph, and kmh?
They all mean the same thing - kilometers per hour. km/h is the official SI notation with a slash. kph follows the same pattern as mph, with one letter per word. kmh drops the slash entirely. All three are used interchangeably in weather forecasts, speed signs, and vehicle specs. If you're searching for "m/s to kph" or "m/s to kmh", this converter gives you exactly that result.
Quiz: how well do you know m/s conversions?
1. What is the exact factor to convert meters per second (m/s) to kilometers per hour (km/h)?
2. According to the reference table on this page, what is 10 m/s in ft/s?
3. Why do physics equations use m/s rather than km/h?
4. A car travels at the common EU motorway speed limit of 100 km/h. What is this in m/s?
5. From the reference table on this page, what real-world event corresponds to 17 m/s (61.2 km/h)?