Speed Converter

Miles per hour, kilometers per hour, meters per second, knots and more.

📖 Read the full guide: Speed Units: Why Sailors and Pilots Use Knots In-depth article explaining the math and real-world context. →

Speed Unit Quick References

Conversion	Value
1 mph	1.609 km/h = 0.447 m/s
1 km/h	0.621 mph = 0.278 m/s
1 m/s	3.6 km/h = 2.237 mph
1 knot (kn)	1.852 km/h = 1.151 mph (aviation, maritime)
1 ft/s	0.682 mph = 0.305 m/s
1 Mach (sea level)	~343 m/s = 1,235 km/h = 767 mph
Speed of light (c)	299,792.458 km/s (exact by SI definition)

Notable Speed Records

Usain Bolt's 100m record — 9.58s = 37.58 km/h (peak ~44 km/h)
Cheetah — up to ~120 km/h in short bursts
Peregrine falcon — over 320 km/h in stooping dive (fastest animal)
Bullet train (Shinkansen) — operational 320 km/h, test 603 km/h (Maglev)
Bugatti Chiron Super Sport — record 490 km/h
Concorde cruise — 2,179 km/h ≈ Mach 2.04
SR-71 Blackbird — 3,540 km/h (fastest manned air-breathing aircraft)
Parker Solar Probe — 692,000 km/h (fastest human-made object, near Sun)

Why Knots in Aviation/Maritime?

One knot equals one nautical mile per hour, and 1 nautical mile = 1 minute of arc of latitude on Earth. This makes navigation math clean: traveling 60 knots due north = 1 degree of latitude per hour. The convention is preserved in modern GPS-based navigation even though pilots and sailors no longer plot positions by latitude/longitude manually.