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🏃 Speed Converter

Convert between meters per second, kilometers per hour, miles per hour, feet per second, knots, and Mach (speed of sound) — all bidirectional, all live. Type in any field and every other one updates instantly.

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100 km/h 60 mph 10 m/s 20 knots Mach 1 (sound) Walking (5 km/h)
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About the Speed Converter

The Speed Converter turns any speed or velocity into every other common unit at once — kilometers per hour, miles per hour, meters per second, feet per second, knots, and Mach. Type in any field and every other one updates instantly.

Everything runs in your browser. Nothing you type leaves the device.

Common uses

  • Driving & road speed limits — US uses mph, most of the world uses km/h.
  • Running & cycling — pace and cadence in km/h vs mph.
  • Sailing & aviation — nautical speeds use knots universally.
  • Physics & engineering — SI velocity in m/s.
  • Aerospace & supersonic — Mach number for aircraft and rocket speeds.

Supported units

Meter per second (m/s) — the SI base unit. Used across physics, engineering, and scientific writing.

Kilometer per hour (km/h) — the everyday metric road-speed unit. Standard everywhere except the US and UK.

Mile per hour (mph) — the US and UK road-speed unit. Also used in weather, wind, and sport.

Foot per second (ft/s) — used in US ballistics, projectile physics, and some engineering.

Knot (kn or kt) — one nautical mile per hour. Universal in aviation and maritime navigation. 1 nautical mile = 1852 m exactly.

Mach — a ratio, not a fixed speed. Mach 1 equals the local speed of sound. At sea level, dry air at 20 °C, sound travels at about 343 m/s. This tool uses 343 m/s as the reference; actual local Mach 1 varies with air temperature, pressure, and humidity.

Exact conversion ratios

  • 1 km/h = 1000 / 3600 m/s ≈ 0.277778 m/s
  • 1 mph = 1609.344 / 3600 m/s = 0.44704 m/s exactly
  • 1 ft/s = 0.3048 m/s exactly
  • 1 knot = 1852 / 3600 m/s ≈ 0.514444 m/s
  • 1 mph = 1.609344 km/h exactly
  • 1 km/h ≈ 0.621371 mph
  • 1 knot ≈ 1.852 km/h ≈ 1.15078 mph
  • Mach 1 (reference) ≈ 343 m/s ≈ 1235 km/h ≈ 767 mph

Rules of thumb

  • Walking — about 5 km/h (3 mph) — 1.4 m/s.
  • Running (moderate) — 10 km/h (6.2 mph) — 2.8 m/s.
  • Marathon world record pace — about 21 km/h (13 mph).
  • City driving — 50 km/h (~31 mph) is standard urban limit in most countries.
  • Highway driving — 100 km/h ≈ 62 mph; 65 mph ≈ 105 km/h.
  • Commercial airliner cruise — around 900 km/h (560 mph, Mach ~0.85).
  • Speed of sound at sea level — Mach 1 ≈ 1235 km/h (767 mph).

Privacy

All conversion runs client-side. Your input never leaves your browser.

Frequently asked questions

Multiply km/h by 0.621371. So 100 km/h × 0.621371 ≈ 62.14 mph. The exact ratio comes from 1 mile = 1.609344 km.
Multiply mph by 1.609344. Example: 60 mph × 1.609344 = 96.56 km/h. A quick mental shortcut: multiply by 1.6.
One knot is one nautical mile per hour. Used universally in aviation and maritime navigation. 1 knot = 1.852 km/h = 1.15078 mph exactly (based on the international definition of 1 nautical mile = 1852 m).
Mach 1 is the local speed of sound. At sea level in dry air at 20 °C it is about 343 m/s, or roughly 1235 km/h / 767 mph. The actual value varies with air temperature, pressure, and humidity — but 343 m/s is the standard textbook reference.
No. Speed conversion is arithmetic — no server round-trip is needed and none is made.