Convert between miles per hour, kilometers per hour, knots, and meters per second instantly. Includes speed of sound, Mach numbers, running pace, and aviation speed references.
Common speed equivalents across units and real-world benchmarks
Enter a speed in mph, km/h, knots, or m/s and get instant accurate conversions across all units.
Open Unit Converter →All speed conversions chain through meters per second (m/s) as the SI base unit:
mph to km/h: km/h = mph × 1.60934
km/h to mph: mph = km/h × 0.62137
mph to m/s: m/s = mph × 0.44704
km/h to m/s: m/s = km/h ÷ 3.6
knots to km/h: km/h = knots × 1.852
knots to mph: mph = knots × 1.15078
Driving across borders requires understanding speed limit units. US limits are in mph; most of the world uses km/h:
US Interstate highway: typically 65–75 mph = 104–121 km/h
US urban roads: 25–35 mph = 40–56 km/h
German Autobahn (recommended): 130 km/h = 80.8 mph
UK motorways: 70 mph = 113 km/h (UK uses mph like the US)
European urban speed limit: 50 km/h = 31 mph
French highways: 130 km/h = 80.8 mph (110 in rain)
A useful approximation: multiply mph by 1.6 to get km/h. So 30 mph ≈ 48 km/h (actual: 48.3), 70 mph ≈ 112 km/h (actual: 112.7). The 5/8 reciprocal works well: 80 km/h ≈ 80 × 5/8 = 50 mph (actual: 49.7 mph).
One knot equals exactly 1 nautical mile per hour. Nautical miles are used in navigation because they correspond to geographic coordinates — 1 nautical mile = 1 arcminute of latitude = 1/60 of a degree. This makes position calculations and navigation mathematics more elegant when using knots.
Common speed references in knots:
Commercial aircraft cruise: ~480–500 knots (552–575 mph / 889–926 km/h)
Corporate jets: 400–500 knots
Large cargo ships: 12–25 knots
Speed boats: 50–70 knots
Wind speeds (hurricane force): above 64 knots (74 mph / 119 km/h)
Calm breeze: 1–5 knots
Mach number expresses speed as a multiple of the speed of sound. Mach 1 is the speed of sound. The actual speed varies with altitude and air temperature:
Sea level (20°C): Mach 1 = 767 mph = 1,235 km/h = 343 m/s = 667 knots
At 35,000 ft (cruising altitude): Mach 1 ≈ 660 mph = 1,062 km/h (colder air = slower sound)
Notable speed milestones:
Sound barrier (Mach 1): 767 mph / 1,235 km/h at sea level
SR-71 Blackbird (record holder): Mach 3.3 = ~2,200 mph
X-15 experimental aircraft: Mach 6.7 = ~4,520 mph
Parker Solar Probe (space): ~430,000 mph = Mach 560+
Runners in the US track pace in minutes per mile; most international runners use minutes per kilometer. Converting between them requires the standard mile-to-km conversion:
Min/mile to min/km: divide by 1.60934. A 9:00/mile pace = 5:35/km
Min/km to min/mile: multiply by 1.60934. A 6:00/km pace = 9:39/mile
Common pace conversions for runners:
5:00/km = 8:03/mile | 5:30/km = 8:51/mile | 6:00/km = 9:39/mile
8:00/mile = 4:58/km | 9:00/mile = 5:35/km | 10:00/mile = 6:13/km
For context: elite marathon runners race at ~2:50–3:00/km (4:30–4:50/mile). A sub-4-hour marathon requires sustaining better than 5:41/km (9:09/mile) for 42.2 km.
Multiply mph by 1.60934 for km/h. Multiply km/h by 0.62137 for mph. 60 mph = 96.6 km/h. 100 km/h = 62.1 mph. Quick mental estimate: mph × 1.6 or km/h × 0.625.
1 knot = 1 nautical mile/hour = 1.852 km/h = 1.151 mph. Used because nautical miles correspond to latitude coordinates. Commercial aircraft cruise at ~500 knots. Wind speeds use knots in weather and aviation.
At sea level (20°C): Mach 1 = 767 mph = 1,235 km/h = 343 m/s. At cruising altitude (35,000 ft): ~660 mph = 1,062 km/h (colder air slows sound). Speed of sound decreases with altitude.
Divide min/mile by 1.60934 to get min/km. Multiply min/km by 1.60934 for min/mile. 9:00/mile = 5:35/km. 5:00/km = 8:03/mile.