Result in km/h
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Equivalent speed
Accurate speed conversion between m/s (metres per second) and km/h (kilometres per hour) — and back
Convert m/s to km/h instantly using the exact factor of 3.6. Full multi-unit breakdown into km/h, mph, knots, ft/s, and Mach — all in one free tool for 2026.
Professional speed conversion for physics, engineering, meteorology, sport science, automotive, and aviation — with all major speed units in one tool
The conversion between metres per second and kilometres per hour is derived from two exact definitions: 1 km = 1,000 m (exact) and 1 hour = 3,600 seconds (exact). Therefore: 1 m/s = 1 m/s × (1 km / 1,000 m) × (3,600 s / 1 hr) = 3,600/1,000 = 3.6 km/h exactly. Conversely, 1 km/h = 1,000/3,600 m/s = 5/18 m/s exactly. The factor of 3.6 is one of the most important constants in everyday physics and engineering — the m/s-to-km/h conversion is encountered daily in weather forecasting, road safety, sports timing, fluid dynamics, and vehicle performance specifications worldwide.
Switch instantly between m/s → km/h and km/h → m/s conversion modes. The results panel simultaneously displays the equivalent speed in six units — km/h, m/s, miles per hour (mph), knots (kn), feet per second (ft/s), and Mach number (at sea level, 15°C) — giving complete cross-unit context from a single input. This is especially useful for scientists working in SI units (m/s) who need road speed equivalents (km/h or mph), meteorologists converting wind speed between m/s and km/h, and pilots or mariners needing knot equivalents — all from a single entry.
The m/s ↔ km/h conversion is critical across many fields: Physics & engineering — SI calculations use m/s; road speeds and specifications use km/h; Meteorology & weather — wind speeds reported in km/h (public) and m/s (scientific); Automotive — speedometers in km/h; engine/test data in m/s; Sport science — sprint speeds (100m in 9.58s = 10.44 m/s = 37.6 km/h); swimming and cycling performance; Aviation — converting m/s to knots and Mach; Fluid dynamics — flow velocities in m/s converted to km/h for reporting; Ballistics & projectile physics — muzzle velocity in m/s.
Select conversion direction, enter your speed value, and get instant multi-unit results
The metre per second (m/s) is the SI coherent derived unit of speed — defined as one metre of distance per one second of time. It is the standard unit for speed and velocity in all scientific, engineering, and physics contexts. The kilometre per hour (km/h), also written as kph, is the most widely used speed unit in everyday life worldwide — used on road signs, vehicle speedometers, weather reports, and sports timing in all countries that use the metric system. The two units are directly related: since 1 km = 1,000 m and 1 hour = 3,600 seconds, the exact relationship is 1 m/s = 3.6 km/h.
To understand the scale: a brisk walking pace is approximately 1.4 m/s (5 km/h); a recreational cyclist rides at about 5–8 m/s (18–29 km/h); a city speed limit of 50 km/h = 13.9 m/s; a typical highway speed of 100 km/h = 27.78 m/s; Usain Bolt's world record 100m sprint averaged 10.44 m/s (37.58 km/h) with a peak speed of approximately 12.4 m/s (44.7 km/h). The speed of sound at sea level (15°C, standard atmosphere) is approximately 340.29 m/s = 1,225 km/h = Mach 1. Light travels at approximately 299,792,458 m/s — exactly, by definition of the SI metre.
Example: 10 m/s × 3.6 = 36 km/h | 100 km/h ÷ 3.6 = 27.78 m/s
1 m/s = 3.6 km/h | 1 km/h = 0.2778 m/s | 1 m/s = 2.237 mph | 1 m/s = 1.944 knots | Mach 1 ≈ 340.29 m/s ≈ 1,225 km/h
To convert metres per second to kilometres per hour, multiply by 3.6 exactly. To convert km/h back to m/s, divide by 3.6 (or multiply by 5/18). Here are three practical worked examples:
Input: 100 km/h (highway limit)
Formula: 100 ÷ 3.6
= 27.78 m/s
= typical motorway cruising speed
Input: 10.44 m/s (world 100m record avg.)
Formula: 10.44 × 3.6
= 37.58 km/h
= Usain Bolt average race speed
Input: 20 m/s (strong gale-force wind)
Formula: 20 × 3.6
= 72 km/h
= Beaufort scale 9 (strong gale)
m/s → km/h: Multiply by 3.6. Shortcut: multiply by 4 then subtract 10% for a quick estimate. Example: 25 m/s × 4 = 100, minus 10% = 90 km/h (exact = 90 km/h ✓). km/h → m/s: Divide by 3.6. Shortcut: multiply by 5, then divide by 18. Example: 90 km/h × 5 = 450, ÷ 18 = 25 m/s (exact ✓). Key anchor values: 1 m/s = 3.6 km/h; 10 m/s = 36 km/h; 100 m/s = 360 km/h. Road speeds in m/s: 30 km/h = 8.33 m/s; 50 km/h = 13.89 m/s; 80 km/h = 22.22 m/s; 100 km/h = 27.78 m/s; 120 km/h = 33.33 m/s; 130 km/h = 36.11 m/s. Weather Beaufort scale: Beaufort 3 (gentle breeze) = 3.4–5.4 m/s = 12–19 km/h; Beaufort 6 (strong breeze) = 10.8–13.8 m/s = 39–49 km/h; Beaufort 12 (hurricane) ≥ 32.7 m/s = ≥118 km/h. Physics shortcut: m/s × 18/5 = km/h; km/h × 5/18 = m/s — both exact fractions.
Complete reference table from slow walking pace through supersonic speeds, with km/h, mph, knots, ft/s, and Mach equivalents plus real-world context. Desktop shows the full table; mobile shows grouped cards.
| Metres/sec (m/s) | Km/hr (km/h) | Miles/hr (mph) | Knots (kn) | Feet/sec (ft/s) | Real-World Reference |
|---|---|---|---|---|---|
| 0.5 m/s | 1.8 km/h | 1.12 mph | 0.97 kn | 1.64 ft/s | Slow amble / drift |
| 1.0 m/s | 3.6 km/h | 2.24 mph | 1.94 kn | 3.28 ft/s | Slow walk |
| 1.4 m/s | 5.0 km/h | 3.11 mph | 2.72 kn | 4.59 ft/s | Average walking pace |
| 2.0 m/s | 7.2 km/h | 4.47 mph | 3.89 kn | 6.56 ft/s | Fast walk / slow jog |
| 3.0 m/s | 10.8 km/h | 6.71 mph | 5.83 kn | 9.84 ft/s | Easy running pace |
| 4.0 m/s | 14.4 km/h | 8.95 mph | 7.78 kn | 13.12 ft/s | Moderate run / cycling |
| 5.0 m/s | 18.0 km/h | 11.18 mph | 9.72 kn | 16.40 ft/s | Comfortable cycling speed |
| 8.33 m/s | 30.0 km/h | 18.64 mph | 16.20 kn | 27.33 ft/s | 30 km/h — residential zone limit |
| 10.0 m/s | 36.0 km/h | 22.37 mph | 19.44 kn | 32.81 ft/s | Fast bicycle / slow scooter |
| 10.44 m/s | 37.58 km/h | 23.35 mph | 20.29 kn | 34.25 ft/s | Usain Bolt avg. 100m world record |
| 13.89 m/s | 50.0 km/h | 31.07 mph | 27.00 kn | 45.57 ft/s | 50 km/h — city speed limit |
| 20.0 m/s | 72.0 km/h | 44.74 mph | 38.88 kn | 65.62 ft/s | Strong gale (Beaufort 9) |
| 22.22 m/s | 80.0 km/h | 49.71 mph | 43.20 kn | 72.91 ft/s | 80 km/h — rural road limit |
| 27.78 m/s | 100.0 km/h | 62.14 mph | 54.00 kn | 91.13 ft/s | 100 km/h — highway / motorway limit |
| 33.33 m/s | 120.0 km/h | 74.56 mph | 64.80 kn | 109.36 ft/s | 120 km/h — autobahn / high-speed road |
| 55.56 m/s | 200.0 km/h | 124.27 mph | 108.00 kn | 182.26 ft/s | 200 km/h — high-speed train / sports car |
| 83.33 m/s | 300.0 km/h | 186.41 mph | 162.01 kn | 273.38 ft/s | 300 km/h — TGV / bullet train |
| 170.0 m/s | 612.0 km/h | 380.3 mph | 330.5 kn | 557.7 ft/s | Mach 0.5 — subsonic aircraft |
| 340.29 m/s | 1,225.1 km/h | 761.2 mph | 661.5 kn | 1,116.5 ft/s | Mach 1 — speed of sound (sea level, 15°C) |
| 680.58 m/s | 2,450.1 km/h | 1,522.4 mph | 1,323.0 kn | 2,232.9 ft/s | Mach 2 — supersonic jet (e.g., Concorde) |
🟢 Green = walking / human-scale speeds | 🟧 Orange = road / vehicle speeds | 🔵 Blue = high-speed / aviation
Wind speed is one of the most common everyday applications of the m/s ↔ km/h conversion. The World Meteorological Organisation (WMO) specifies wind speed in m/s for scientific and synoptic meteorological reports (METAR, weather buoys, radiosonde data), while public weather forecasts and storm warnings are typically reported in km/h in metric countries. The Beaufort wind scale: B1 (1–3 km/h = 0.3–0.8 m/s); B3 gentle breeze (12–19 km/h = 3.4–5.4 m/s); B6 strong breeze (39–49 km/h = 10.8–13.8 m/s); B8 gale (62–74 km/h = 17.2–20.6 m/s); B10 storm (89–102 km/h = 24.5–28.3 m/s); B12 hurricane force (≥118 km/h = ≥32.7 m/s). Tropical cyclone categories are defined in both km/h and m/s. Meteorologists and emergency services work daily with both units, requiring rapid exact conversion between scientific and public-facing wind speed reports.
Vehicle dynamics, road safety research, and automotive engineering use both m/s and km/h. Braking distance physics is calculated in m/s (kinetic energy = ½mv²), then translated to km/h for highway safety reporting. Stopping distances at 100 km/h (27.78 m/s): dry road ≈ 40–55 m; wet road ≈ 70–85 m. Reaction distance at 100 km/h at 1-second reaction time = 27.78 m. Crash test speeds: standard Euro NCAP frontal test at 56 km/h = 15.56 m/s; side pole test at 29 km/h = 8.06 m/s. Speed camera radar guns measure in km/h or mph; the underlying physics (Doppler shift, time-of-flight) is calculated in m/s. Vehicle acceleration: 0–100 km/h (0–27.78 m/s) in 3.5 seconds = average acceleration of 7.94 m/s². Tyre speed ratings (e.g., V = 240 km/h = 66.67 m/s) specify maximum safe operating speed.
Speed conversion is fundamental in performance sport analysis. Athletics: Usain Bolt 100m world record (9.58 s) = average 10.44 m/s = 37.58 km/h; peak speed ≈ 12.4 m/s = 44.7 km/h. Marathon world record pace (2:00:35) = approximately 5.84 m/s = 21.03 km/h. Swimming: world record 50m freestyle ≈ 2.39 m/s = 8.60 km/h. Cycling: Tour de France sprint speeds ≈ 19–21 m/s = 68–76 km/h. Soccer: ball speed in a penalty kick ≈ 30–40 m/s = 108–144 km/h; player sprint ≈ 9–10 m/s = 32–36 km/h. Tennis serve: world record ≈ 73.4 m/s = 264 km/h (Sam Groth, 2012). Cricket ball delivery: fast bowler ≈ 40–45 m/s = 144–162 km/h; speed gun readouts are in km/h while biomechanical analysis uses m/s. Sports scientists, coaches, and analysts work continuously across both units when analysing GPS tracking data (m/s) for broadcast reporting (km/h).
Aviation uses multiple speed units requiring conversion from m/s. True airspeed (TAS) and indicated airspeed (IAS) are reported in knots (1 knot = 0.514444 m/s = 1.852 km/h) for international air navigation. Mach number = airspeed / local speed of sound: Mach 1 ≈ 340.29 m/s ≈ 1,225 km/h at sea level (15°C ISA); at cruise altitude (10,000 m, -50°C), Mach 1 ≈ 295 m/s ≈ 1,062 km/h. Commercial airliner cruise: Mach 0.78–0.85 ≈ 230–250 m/s ≈ 830–900 km/h. Fighter jet: Mach 2 ≈ 680 m/s ≈ 2,450 km/h. Nautical speed in knots: 1 knot = 1 nautical mile per hour = 1.852 km/h = 0.5144 m/s. Ship cruising speed: 20 knots = 37.04 km/h = 10.29 m/s. Pilots, maritime navigators, and aerospace engineers must convert fluidly between m/s, km/h, knots, and Mach numbers for operational and safety calculations.
In physics and engineering, m/s is the required SI unit for all velocity-dependent calculations, while km/h is often used in specifications, reports, and public-facing outputs. Key physics formulas using m/s: kinetic energy KE = ½mv² (v in m/s, KE in joules); momentum p = mv (kg·m/s); Newton's second law F = ma (m/s²); wave speed v = fλ (f in Hz, λ in metres). Hydraulic engineering: flow velocity in channels, pipes, and rivers is measured and calculated in m/s; flood warning thresholds are converted to km/h for public communication. Fluid dynamics (Reynolds number, Bernoulli equation) requires m/s. Ballistics and projectile motion: muzzle velocity ≈ 370–1,000 m/s = 1,332–3,600 km/h. Rail engineering: track design speeds in km/h; dynamic stress calculations in m/s. Signal processing: vibration and acoustic wave speeds in m/s. Converting between the SI m/s and the practical km/h unit is a constant requirement across all physics and engineering disciplines.
Ocean current speeds, river flow rates, and environmental wind/water measurements use m/s for scientific data and km/h for public reporting. Ocean surface current speeds: typical Gulf Stream ≈ 1.5–2.5 m/s = 5.4–9.0 km/h; average open-ocean currents ≈ 0.1–0.3 m/s = 0.36–1.08 km/h. Tsunami wave speed in deep ocean: ≈ 200–250 m/s = 720–900 km/h; in shallow water ≈ 30–50 m/s. River flow (flood monitoring): bankfull velocity ≈ 1.5–3 m/s = 5.4–10.8 km/h; flash flood ≈ 5–10 m/s = 18–36 km/h. Tidal current data from ADCP instruments in m/s; coastal navigation uses knots. Air quality monitoring: wind speed at station in m/s; reported in km/h on public dashboards. Climate science: atmospheric jet stream speeds ≈ 30–70 m/s = 108–252 km/h. Environmental engineers, hydrologists, and oceanographers convert m/s measurements to km/h regularly when preparing reports, issuing warnings, or comparing data with public-facing reference standards.
1 m/s = 3.6 km/h (exact). 1 km/h = 5/18 m/s = 0.27̄ m/s (exact). 1 m/s = 2.23694 mph. 1 m/s = 1.94384 knots. 1 m/s = 3.28084 ft/s. Mach 1 ≈ 340.29 m/s ≈ 1,225 km/h (sea level, 15°C). Speed of light = 299,792,458 m/s (exact, by definition). Common road speeds in m/s: 30 km/h = 8.33 m/s; 50 km/h = 13.89 m/s; 80 km/h = 22.22 m/s; 100 km/h = 27.78 m/s; 120 km/h = 33.33 m/s; 130 km/h = 36.11 m/s. Quick rule: m/s × 3.6 = km/h; km/h ÷ 3.6 = m/s. Alternatively: km/h × 5/18 = m/s; m/s × 18/5 = km/h. Exact fractions — no approximation needed.
Kilometres per hour (km/h) and miles per hour (mph) are both called "speed" but differ significantly: 1 mph = 1.60934 km/h and 1 km/h = 0.62137 mph. A speed limit of 100 mph (UK motorway) = 160.9 km/h; a speed limit of 100 km/h (most metric countries) = 62.1 mph — very different speeds. The USA, UK, and a handful of other countries use mph on road signs and speedometers; virtually all other countries use km/h. GPS devices, radar guns, and some imported vehicles may default to mph instead of km/h — always verify the unit on any speed-measuring device. In physics and SI calculations, always use m/s — never mix mph and km/h without converting first, as this has caused real-world engineering errors (including the infamous 1999 NASA Mars Climate Orbiter loss caused by mixing Imperial and metric units).
The International Bureau of Weights and Measures (BIPM) defines the metre per second (m/s) as the SI coherent derived unit of speed and velocity — derived from the SI base units of length (metre) and time (second). The 9th edition SI Brochure (2019) confirms the metre and second definitions underpinning all speed calculations. The kilometre per hour (km/h) is a non-SI unit accepted for use with the SI, derived from the kilo- prefix (10³) and the hour (3,600 s), giving the exact conversion factor 1 km/h = 1,000/3,600 m/s = 5/18 m/s.
Visit BIPM →The World Meteorological Organisation (WMO) standardises wind speed measurement and reporting globally. WMO Technical Regulations specify wind speed in m/s for official meteorological observations and reports (SYNOP, METAR, TEMP). National weather services translate these to km/h or knots for public communication. The WMO also defines the Beaufort scale reference values in m/s, and publishes guidelines for anemometer calibration, averaging periods (standard 10-minute mean wind speed), and gust definitions — all expressed in m/s as the primary scientific unit.
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