Speed Converter
Speed unit conversion reference
| From | To km/h | To mph | To m/s | To knots |
|---|---|---|---|---|
| 1 km/h | 1 | 0.6214 | 0.2778 | 0.5400 |
| 1 mph | 1.6093 | 1 | 0.4470 | 0.8690 |
| 1 m/s | 3.6 | 2.2369 | 1 | 1.9438 |
| 1 knot | 1.8520 | 1.1508 | 0.5144 | 1 |
| 1 Mach | 1,234.8 | 767.3 | 343 | 666.7 |
Notable speed references
- Walking pace: 5 km/h (3.1 mph)
- World record 100m sprint: 44.7 km/h (27.8 mph) — Usain Bolt
- City speed limit (India/UK): 50 km/h (31 mph)
- Highway speed limit (US): 120–130 km/h (75–80 mph)
- Commercial aircraft cruise: 900–950 km/h (560–590 mph, ~Mach 0.85)
- Sound at sea level (Mach 1): 343 m/s = 1,234 km/h = 767 mph
- Light speed: 299,792 km/s = 1,079,252,848 km/h
How to get the most accurate result
Enter values as precisely as possible — rounding inputs produces rounding errors in the output. Use decimal points for fractional values rather than rounding to whole numbers. If the calculator produces an unexpected result, check that you have entered values in the correct fields and units. All calculations update instantly as you type. Pairs well with the Length Converter and the Pace Calculator.
Understanding your result
The calculated result is based on standard formulas verified against authoritative sources listed at the bottom of this page. For critical decisions — financial, medical, or engineering — treat the result as an informed estimate and consult a qualified professional. Calculator outputs should supplement expert advice, not replace it.
Frequently asked questions about speed conversion
What is a knot? A knot is one nautical mile per hour (1.852 km/h = 1.151 mph). It is used in maritime and aviation navigation because nautical miles correspond to one minute of arc of latitude, making navigation calculations simpler. Ships and aircraft express speed in knots, altitude in feet, and distance in nautical miles.
What does Mach 1 mean? Mach 1 is the speed of sound in air at sea level at 15°C — approximately 343 m/s (1,234 km/h, 767 mph). The Mach number changes with altitude and temperature. At 35,000 feet (typical cruise altitude), the speed of sound drops to about 1,062 km/h, so aircraft at Mach 0.85 are moving at about 903 km/h.
Speed unit conversion table
| From | km/h | mph | m/s | Knots | Mach |
|---|---|---|---|---|---|
| 1 km/h | 1 | 0.6214 | 0.2778 | 0.5400 | 0.000816 |
| 1 mph | 1.6093 | 1 | 0.4470 | 0.8690 | 0.001314 |
| 1 m/s | 3.6 | 2.2369 | 1 | 1.9438 | 0.002915 |
| 1 knot | 1.852 | 1.1508 | 0.5144 | 1 | 0.001500 |
| 1 Mach (sea level) | 1,234.8 | 767.3 | 343 | 666.7 | 1 |
How fast is Mach 1, the speed of light, and a Formula 1 car in km/h?
| Subject | km/h | mph | Notes |
|---|---|---|---|
| Average walking pace | 4–5 | 2.5–3.1 | Comfortable adult walking |
| Recreational jogging | 8–12 | 5–7.5 | Easy run |
| Usain Bolt (100 m WR peak) | 44.7 | 27.8 | 2009 Berlin — fastest human recorded |
| Cheetah (top speed) | 112–120 | 70–75 | Fastest land animal |
| Urban speed limit (India/UK) | 50 | 31 | Standard urban limit |
| Indian expressway maximum | 120 | 75 | National Highway expressways |
| Commercial aircraft (cruise) | 900–950 | 560–590 | ~Mach 0.85 |
| Sound at sea level (Mach 1) | 1,234.8 | 767.3 | 20°C, dry air |
Speed limits by country
| Country | Urban (km/h) | Rural (km/h) | Motorway (km/h) |
|---|---|---|---|
| India | 50 | 100 | 120 |
| United States | 40–55 | 88–105 | 105–130 |
| United Kingdom | 48 (30 mph) | 96 (60 mph) | 112 (70 mph) |
| Germany | 50 | 100 | No limit (advisory 130) |
| Australia | 50–60 | 100–110 | 110–130 |
Frequently asked questions
How many mph is 100 km/h? 100 km/h = 62.14 mph. Mental shortcut: multiply km/h by 0.621, or mph by 1.609. 60 mph ≈ 96.6 km/h — useful when driving abroad.
What is a knot? One nautical mile per hour = 1.852 km/h = 1.151 mph. Based on Earth's geometry (one minute of arc of latitude), making navigation charts simpler. Standard in aviation and maritime contexts worldwide.
What is Mach 1? The speed of sound at sea level = 343 m/s = 1,234.8 km/h at 20°C. Decreases with altitude — at 35,000 ft, Mach 1 ≈ 1,062 km/h. Supersonic = above Mach 1; hypersonic = above Mach 5.
Real-world speed reference points
| Speed Reference | km/h | mph | m/s | Knots |
|---|---|---|---|---|
| Average walking pace | 5 | 3.1 | 1.4 | 2.7 |
| Jogging pace | 8–10 | 5–6.2 | 2.2–2.8 | 4.3–5.4 |
| Cycling (leisure) | 15–20 | 9.3–12.4 | 4.2–5.6 | 8.1–10.8 |
| Usain Bolt (world record) | 44.7 | 27.8 | 12.4 | 24.1 |
| City speed limit (typical) | 50 | 31 | 13.9 | 27 |
| Highway speed limit (US) | 105–113 | 65–70 | 29–31 | 57–61 |
| Formula 1 top speed | ~372 | ~231 | ~103 | ~201 |
| Commercial aircraft (cruise) | 900–920 | 560–570 | 250–256 | 486–497 |
| Speed of sound (sea level, 15°C) | 1,235 | 767 | 343 | 667 |
| Concorde (retired) | 2,179 | 1,354 | 605 | 1,176 |
| Earth orbital velocity | 107,000 | 66,500 | 29,800 | 57,800 |
| Speed of light (vacuum) | 1,079,252,849 | 670,616,629 | 299,792,458 | 582,749,918 |
How do you convert between km/h, mph, and m/s?
| From | To | Formula |
|---|---|---|
| km/h | mph | × 0.621371 |
| mph | km/h | × 1.60934 |
| km/h | m/s | ÷ 3.6 |
| m/s | km/h | × 3.6 |
| knots | km/h | × 1.852 |
| km/h | knots | ÷ 1.852 |
| mph | m/s | × 0.44704 |
| Mach 1 | km/h | = 1,235 km/h (at sea level, 15°C) |
Sources & References
Sources: BIPM SI Units — metre and second definitions; ISO 80000-3 (Quantities and units — Space and time); ICAO Standard Atmosphere — speed of sound definition.
Speed limits by country and vehicle type
Speed limits are set in either km/h or mph depending on the country. Use this converter to understand speed limits when driving abroad or reading international vehicle specs.
| Country | Urban (km/h) | Rural (km/h) | Motorway (km/h) | Unit |
|---|---|---|---|---|
| India | 30–50 | 70–100 | 100–120 | km/h |
| United States | 25–35 mph (40–56 km/h) | 55–65 mph (88–105) | 65–75 mph (105–121) | mph |
| United Kingdom | 30 mph (48 km/h) | 60 mph (97) | 70 mph (113) | mph |
| Germany (Autobahn) | 50 | 100 | No general limit (advisory 130) | km/h |
| Australia | 50 | 100 | 110 | km/h |
| UAE | 60 | 120 | 140 | km/h |
| France | 50 | 80 | 130 (110 in rain) | km/h |
Wind speed: Beaufort scale reference
| Beaufort No. | Description | Speed (km/h) | Speed (mph) | Observed Effects |
|---|---|---|---|---|
| 0 | Calm | <1 | <1 | Smoke rises vertically |
| 3 | Gentle breeze | 12–19 | 8–12 | Leaves in motion; light flag extended |
| 5 | Fresh breeze | 29–38 | 19–24 | Small trees sway; waves on inland waters |
| 7 | Near gale | 50–61 | 32–38 | Whole trees in motion; difficult to walk |
| 9 | Strong gale | 75–88 | 47–54 | Slight structural damage; chimney pots fall |
| 12 | Hurricane force | ≥118 | ≥73 | Devastating destruction; extremely rare on land |
| From | To | Formula | Example |
|---|---|---|---|
| km/h | mph | ÷ 1.60934 | 100 km/h = 62.1 mph |
| mph | km/h | × 1.60934 | 60 mph = 96.6 km/h |
| m/s | km/h | × 3.6 | 10 m/s = 36 km/h |
| km/h | m/s | ÷ 3.6 | 72 km/h = 20 m/s |
| knots | km/h | × 1.852 | 100 knots = 185.2 km/h |
| km/h | knots | ÷ 1.852 | 200 km/h = 108 knots |
Sources: World Meteorological Organization Beaufort scale definitions; national road traffic authority speed limit databases; BIPM SI unit definitions.
Speed limits around the world: km/h and mph comparison
Speed limits vary significantly by country and road type. Most of the world uses km/h; the United States, United Kingdom, and a few others use mph:
| Country | Urban (city) | Rural (highway) | Motorway / Freeway |
|---|---|---|---|
| India | 50 km/h | 100 km/h | 120 km/h |
| Germany (Autobahn) | 50 km/h | 100 km/h | 130 km/h recommended (unlimited sections exist) |
| USA | 25–35 mph (40–56 km/h) | 55–65 mph (88–105 km/h) | 65–80 mph (105–129 km/h) |
| UK | 30 mph (48 km/h) | 60 mph (97 km/h) | 70 mph (113 km/h) |
| Australia | 50 km/h | 100 km/h | 110 km/h |
| UAE / Saudi Arabia | 60–80 km/h | 120 km/h | 140 km/h |
Wind speed: Beaufort scale reference
The Beaufort scale describes wind speed from 0 (calm) to 12 (hurricane force). Used in weather forecasts and sailing conditions:
| Beaufort # | Description | km/h | mph | m/s |
|---|---|---|---|---|
| 0 | Calm | < 1 | < 1 | 0–0.2 |
| 1–2 | Light air / Light breeze | 1–11 | 1–7 | 0.3–3.3 |
| 3–4 | Gentle / Moderate breeze | 12–28 | 8–18 | 3.4–7.9 |
| 5–6 | Fresh / Strong breeze | 29–49 | 19–31 | 8.0–13.8 |
| 7–8 | Near gale / Gale | 50–74 | 32–46 | 13.9–20.7 |
| 9–10 | Strong gale / Storm | 75–102 | 47–63 | 20.8–28.4 |
| 11 | Violent storm | 103–117 | 64–72 | 28.5–32.6 |
| 12 | Hurricane | ≥ 118 | ≥ 73 | ≥ 32.7 |
Speed of common reference points
| Object / Event | Speed (km/h) | Speed (mph) | Speed (m/s) |
|---|---|---|---|
| Walking pace | 5 | 3.1 | 1.4 |
| Usain Bolt (100m world record) | 44.7 | 27.8 | 12.4 |
| Cheetah (top speed) | 112 | 70 | 31.1 |
| Sound (sea level, 20°C) | 1,235 | 767 | 343 |
| Commercial aircraft (cruise) | 900 | 560 | 250 |
| Light (in vacuum) | 1,079,252,848 | 670,616,629 | 299,792,458 |