Conversion
Speed Converter
Convert between km/h, mph, m/s, knots, ft/s, and Mach — all results shown simultaneously.
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Formula: BIPM / NISTLast verified July 2026
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Quick reference — Kilometres/hour conversions
| km/h | m/s | mph | kn | ft/s |
|---|---|---|---|---|
| 1 | 0.27777778 | 0.62137119 | 0.53995727 | 0.91134442 |
| 5 | 1.388889 | 3.106856 | 2.699786 | 4.556722 |
| 10 | 2.777778 | 6.213712 | 5.399573 | 9.113444 |
| 25 | 6.944444 | 15.53428 | 13.498932 | 22.78361 |
| 50 | 13.888889 | 31.06856 | 26.997863 | 45.567221 |
| 100 | 27.777778 | 62.137119 | 53.995727 | 91.134442 |
Worked Examples
Speed limit: 100 km/h in mph
The most common highway speed limit in Europe is 100 km/h = 62.14 mph. The UK limit is 70 mph = 112.65 km/h. UAE highways are typically 120 km/h = 74.56 mph.
Aircraft cruising speed in Mach
A commercial airliner cruises at around 900 km/h = 250 m/s = 559 mph ≈ Mach 0.85. Mach 1 (the speed of sound at sea level) = 340.29 m/s = 1,225 km/h = 761 mph.
Usain Bolt's top speed
During the 2009 World Championships 100m final, Bolt reached a peak speed of 44.72 km/h = 27.79 mph = 12.42 m/s. That is approximately 0.037 Mach at sea level.
Frequently Asked Questions
~4 min readHow many mph in 100 km/h?▾
62.1371 mph. A useful approximation is to multiply km/h by 0.621 for mph. Conversely, to go from mph to km/h, multiply by 1.609.
What is a knot?▾
A knot is one nautical mile per hour = 1.852 km/h = 1.151 mph. It is used in aviation and maritime contexts because one nautical mile corresponds to one arc-minute of latitude, making navigation calculations simpler on charts.
What is Mach 1?▾
Mach 1 is the speed of sound in dry air at sea level at 20°C — approximately 340.29 m/s = 1,225 km/h = 761 mph. The exact value depends on temperature and altitude; at 30,000 ft (cold, thin air) it is lower — around 295 m/s.
What is the fastest speed ever recorded for a human-made object?▾
The Parker Solar Probe reached approximately 692,000 km/h (430,000 mph) in its close approach to the Sun — around Mach 635. The fastest crewed aircraft was the SR-71 Blackbird at Mach 3.3 = 3,540 km/h = 2,200 mph.
How do I convert km/h to m/s?▾
Divide by 3.6. So 90 km/h ÷ 3.6 = 25 m/s. To go the other way, multiply m/s × 3.6 to get km/h. This works because 1 km = 1,000 m and 1 hour = 3,600 s: km/h × (1000/3600) = m/s.
What speed does UAE law set for highways?▾
UAE federal law sets most urban speed limits at 60–80 km/h and highway limits at 100–120 km/h. Salik-equipped roads may allow up to 120 km/h; specific routes like Sheikh Zayed Road allow 100 km/h in urban sections. Always check posted limits as radars enforce strict tolerances.