Divide by 1.60934: km/h ÷ 1.60934 = mph. Example: 100 km/h = 62.14 mph. Quick approximation: multiply by 0.6 (100 × 0.6 = 60 mph — within 3 %). For the exact reverse, multiply by 1.60934: 60 mph = 96.56 km/h. The exact factor is 1 international mile = 1,609.344 metres, so 1 mph = 1609.344 m/hr = 1.60934 km/h.

60 mph = 96.56 km/h (60 × 1.60934). 100 km/h = 62.14 mph (100 ÷ 1.60934). Other common road values: 30 mph = 48.28 km/h; 70 mph = 112.65 km/h; 120 km/h = 74.56 mph; 80 km/h = 49.71 mph. These come up constantly when comparing speed limits, vehicle specs, and race results across countries that use different unit systems.

Multiply by 3.6: m/s × 3.6 = km/h. Example: 10 m/s = 36 km/h. The factor 3.6 comes from unit analysis: 1 m/s = 1 m/s × (1 km / 1000 m) × (3600 s / 1 hr) = 3.6 km/h. In reverse, divide by 3.6: 72 km/h = 20 m/s. The m/s ↔ km/h pair is the most common conversion in physics classwork, engineering calculations, and scientific papers.

Knots to km/h: kn × 1.852 = km/h. Example: 20 knots = 37.04 km/h. Knots to mph: kn × 1.15078 = mph. Example: 100 knots = 115.08 mph. One knot (kn) is defined as exactly 1 nautical mile per hour, and 1 nautical mile = 1,852 metres. That exact 1.852 ratio comes from the nautical mile's original definition tied to arc-minutes of latitude.

All five measure the same physical quantity — speed — but use different distance and time bases. km/h (kilometers per hour) is the global metric standard for road travel. mph (miles per hour) is used in the US and UK. m/s (meters per second) is the SI base unit, used in physics and science. ft/s (feet per second) appears in US engineering and ballistics. Knots (kn) are nautical miles per hour, the international standard for aviation and marine navigation. They're all linearly related — no offsets, only multiplication factors.

Divide 60 by the speed in km/h: 60 ÷ km/h = min/km. Example: 10 km/h = 6:00 min/km (60 ÷ 10 = 6 minutes per km). 12 km/h = 5:00 min/km; 15 km/h = 4:00 min/km; 20 km/h = 3:00 min/km. For mph to min/mile: 60 ÷ mph = min/mile. Pace and speed are mathematical inverses — a faster speed means a lower (smaller) pace number.

1 km/h = 0.2778 m/s (1 ÷ 3.6). 1 m/s = 3.6 km/h (1 × 3.6). These are the fundamental anchors for the km/h ↔ m/s scale. In physics problems: 72 km/h → 20 m/s; 36 km/h → 10 m/s; 108 km/h → 30 m/s. The 3.6 multiplier is exact — it follows directly from the definitions of the kilometre and the hour (1 km/h = 1000/3600 m/s = 5/18 m/s ≈ 0.2̄7̄ m/s).

ft/s to mph: ft/s × 0.681818 = mph (or multiply by 15/22). Example: 88 ft/s = 60 mph exactly. mph to ft/s: mph × 1.46667 = ft/s. Example: 60 mph = 88 ft/s (60 × 1.46667). The 88 ft/s = 60 mph equivalence is a classic engineering shorthand widely used in US brake testing, ballistics, and traffic collision analysis.

Three steps: (1) Type any speed value — integers and decimals both work (e.g., 65.5 mph, 100 km/h, 5.5 m/s, 250 kn). (2) Select the source unit from the dropdown: km/h, mph, m/s, ft/s, kn, min/km, min/mi, or Mach. (3) All other units update instantly. Tap Copy next to any row to copy that value directly to clipboard. Free, no login, mobile-friendly at untangletools.com/unit/category/speed.

Yes — decimal inputs are fully supported. Examples: 65.5 mph → 105.42 km/h; 5.5 m/s → 19.8 km/h; 1.5 Mach → 1,837 km/h. The tool uses 64-bit floating-point precision throughout — no intermediate rounding. This matters for engineering calculations where 0.01 m/s can be significant, and for running pace conversions where a few seconds per km changes training zones.

Yes — full unit support: km/h, mph, m/s, ft/s, knots (kn), min/km, min/mi, Mach. Each is selectable as the source, and all others output simultaneously. Pace units (min/km, min/mi) are handled correctly as reciprocals of speed — the math is non-obvious, so having a calculator removes the chance of inversion errors. Mach uses the sea-level standard (343 m/s = Mach 1).

Yes. All conversion factors use exact SI-defined or internationally standardised values: 1 mph = 0.44704 m/s exactly (US survey definition); 1 knot = 0.514444 m/s (1852/3600); 1 ft/s = 0.3048 m/s exactly. Mach uses 343 m/s (dry air, 20 °C, sea level). Fully free at untangletools.com/unit/category/speed.

One knot = one nautical mile per hour. A nautical mile is defined as one arc-minute of latitude (1/60 of a degree), making it directly tied to Earth's geometry. This connection makes navigation by latitude/longitude natively compatible with knots — no conversion factor is needed between chart distances and speed. ICAO (aviation) and IMO (maritime) standardised on knots to ensure international interoperability. Changing to km/h would introduce conversion errors at sea and in the air where precise positioning is safety-critical.

Mach 1 at sea level in dry air at 20 °C = 343 m/s = 1,235 km/h = 767 mph. Formula: Mach × 1,235 = km/h (sea level). Note: the speed of sound changes with altitude and temperature — at cruising altitude (−57 °C), Mach 1 ≈ 295 m/s ≈ 1,062 km/h. This is why supersonic fighters express speed as a Mach number rather than a fixed km/h value: 0.85 Mach always means the same fraction of ambient sound speed, regardless of altitude.

min/km to km/h: 60 ÷ pace(min/km) = km/h. Example: 5:00 min/km = 60 ÷ 5 = 12 km/h. km/h to min/km: 60 ÷ km/h = min/km. Example: 10 km/h = 60 ÷ 10 = 6:00 min/km. For min/mile: 60 ÷ mph = min/mile. The relationship is a reciprocal — pace and speed move in opposite directions. This catches people out: going from 5:00 to 4:30 min/km is not a 10 % speed increase; it's 60/4.5 = 13.33 km/h vs 12 km/h — an 11.1 % increase.

100 km/h simultaneously equals: 62.14 mph (÷ 1.60934); 27.78 m/s (÷ 3.6); 91.13 ft/s (× 0.9113); 53.99 knots (÷ 1.852); and 0.0810 Mach at sea level. This is a classic benchmark: it's the speed limit on many European motorways and a common reference in vehicle performance discussions. The converter outputs all of these simultaneously from a single input.

Weather services use inconsistent units: US forecasts use mph, European forecasts use km/h, aviation METARs use knots, and marine bulletins often add Beaufort scale. Beaufort Force 8 (gale) = 34–40 kn = 63–74 km/h = 39–46 mph. Beaufort Force 12 (hurricane) = above 64 kn = 119 km/h = 74 mph. The converter handles km/h, mph, and kn directly — for Beaufort, use the Force 8 boundaries as conversion anchors and interpolate within each band.

Speed units and acceleration units are related but different. If a car accelerates from 0 to 60 mph in 4 seconds: first convert 60 mph to m/s: 60 × 0.44704 = 26.82 m/s. Then divide by time: 26.82 ÷ 4 = 6.71 m/s². In g-forces: 6.71 ÷ 9.81 = 0.68 g. This workflow — convert the speed, then compute acceleration — is used in vehicle dynamics, motorsport, and robotics. The converter handles the speed-unit step; the ÷ time step is separate arithmetic.

Ground speed is how fast an aircraft moves over Earth's surface — GPS-measured, expressed in knots or km/h. Indicated airspeed (IAS) is what the pitot tube reads, corrected for instrument error — used for stall and structural limits. True airspeed (TAS) accounts for air density at altitude; at 35,000 ft, TAS may be 480 kn while IAS reads only 290 kn. A tailwind adds to ground speed but not to airspeed. Converting between these requires both a speed unit conversion and atmospheric data — the converter handles the unit portion (kn ↔ km/h ↔ mph) while a flight computer or E6B handles density altitude corrections.

European and Asian manufacturers publish top speed in km/h; US manufacturers often use mph. To compare: km/h ÷ 1.60934 = mph. Examples: Bugatti Chiron Super Sport limited at 440 km/h = 273 mph; Ford Mustang Shelby GT500 at 290 km/h = 180 mph; Porsche 911 Turbo S at 330 km/h = 205 mph. When one figure is "limited by electronics," the true mechanical maximum is often higher. The converter makes these comparisons instant — paste the manufacturer spec, select km/h or mph, read the other.

The ISS orbits at approximately 27,600 km/h = 17,150 mph = 7,667 m/s = 7.9 Mach (relative to the surface). A fast fighter jet like the F-22 Raptor reaches around Mach 2 ≈ 2,470 km/h = 1,535 mph. The ISS travels roughly 11 times faster than the fastest crewed combat aircraft. At ISS speed, New York to London (5,570 km) takes about 12 minutes. These figures illustrate why Mach and km/h are both needed — jet speeds fit comfortably in km/h, while orbital speeds are more naturally expressed as multiples of Mach or in km/s.