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Convert between km/h, mph, knots, m/s and ft/s.
Convert between km/h, mph, knots, m/s and ft/s.
Enter values above and click Calculate — results will appear here with the formula explained.
Speed units pair a distance with an hour (or second), so their factors inherit exact distance definitions: the mile contributes 1.609344 km to every mph conversion. The knot — one nautical mile per hour — survives from navigation because nautical miles map onto latitude minutes.
Scientists favor meters per second because it slots directly into physics equations: highway speed 100 km/h equals 27.78 m/s, a figure worth internalizing for braking-distance intuition.
Driving abroad is the top use case: UK motorways at 70 mph ≈ 113 km/h, US interstates at 65–75 mph ≈ 105–121 km/h, German autobahn advisory 130 km/h ≈ 81 mph (unlimited sections aside). Rental dashboards may show either unit — convert the limit, not your habit.
Aviation and marine run on knots and Mach: approach speeds ~130–160 knots (≈240–300 km/h), cruise Mach 0.78–0.85 (≈830–900 km/h at altitude), and wind reports in knots worldwide. Converting wind (20-knot crosswind ≈ 37 km/h) matters more for light aircraft than headline speeds.
Athletics lives in pace (min/km) and splits rather than speed, but the conversions connect: 10 km/h running ≈ 6:00/km, 15 km/h ≈ 4:00/km elite tempo, 20 km/h ≈ 3:00/km world-class. Treadmills mixing mph and km/h have caused many interval disasters — verify the unit before the workout.
Everyday anchors: walking ~5 km/h (3.1 mph), cycling commute ~15–20 km/h, city speed limits 30–50 km/h, highway 100–130 km/h, commercial jet ~900 km/h, sound ~1,235 km/h at sea level. Anchoring new figures to walking speed keeps them intuitive.
Convert between km/h, mph, knots, m/s and ft/s. Formula: result = value × (from-factor ÷ to-factor). Example: 120 km/h equals 74.56 mph — worth knowing before setting cruise control on an American interstate signed in mph.
Speed units pair a distance with an hour (or second), so their factors inherit exact distance definitions: the mile contributes 1.609344 km to every mph conversion. The knot — one nautical mile per hour — survives from navigation because nautical miles map onto latitude minutes.
Scientists favor meters per second because it slots directly into physics equations: highway speed 100 km/h equals 27.78 m/s, a figure worth internalizing for braking-distance intuition.
Driving abroad is the top use case: UK motorways at 70 mph ≈ 113 km/h, US interstates at 65–75 mph ≈ 105–121 km/h, German autobahn advisory 130 km/h ≈ 81 mph (unlimited sections aside). Rental dashboards may show either unit — convert the limit, not your habit.
Aviation and marine run on knots and Mach: approach speeds ~130–160 knots (≈240–300 km/h), cruise Mach 0.78–0.85 (≈830–900 km/h at altitude), and wind reports in knots worldwide. Converting wind (20-knot crosswind ≈ 37 km/h) matters more for light aircraft than headline speeds.
Athletics lives in pace (min/km) and splits rather than speed, but the conversions connect: 10 km/h running ≈ 6:00/km, 15 km/h ≈ 4:00/km elite tempo, 20 km/h ≈ 3:00/km world-class. Treadmills mixing mph and km/h have caused many interval disasters — verify the unit before the workout.
Everyday anchors: walking ~5 km/h (3.1 mph), cycling commute ~15–20 km/h, city speed limits 30–50 km/h, highway 100–130 km/h, commercial jet ~900 km/h, sound ~1,235 km/h at sea level. Anchoring new figures to walking speed keeps them intuitive.
120 km/h equals 74.56 mph — worth knowing before setting cruise control on an American interstate signed in mph. A 20-knot crosswind equals 37 km/h — the number that decides light-aircraft go/no-go, not the headline wind speed.
Formulas are standard public references (see our methodology). External standards are cited in the text where they apply.
Last reviewed: September 2026 · Report an error