Knot to Millimeter per Second

A knot is one nautical mile per hour, where a nautical mile equals exactly 1,852 meters. It's the standard speed unit in maritime and aviation contexts.

1 knot = 1 nautical mile/hour = 1,852 m/h = 1.852 km/h = 0.514 m/s. One nautical mile = 1,852 meters exactly.

To km/h: × 1.852. To mph: × 1.151. To m/s: × 0.514. To ft/s: × 1.688.

Ship cruising speeds (cruise ships: 20–25 knots), aircraft speeds (Boeing 747: 490 knots cruise), wind speed in aviation weather reports (METAR), and sailing.

Fastest ship: 60+ knots (naval vessels). Blue whale swim: 5–20 knots. Jet stream winds: 80–140 knots. Hurricane-force winds: 64+ knots.

Saying 'knots per hour' — incorrect! A knot already includes 'per hour.' Just say 'knots.' Also, confusing nautical and statute miles.

1 knot ≈ 1.85 km/h. Roughly: 10 knots ≈ 20 km/h. Remember: knots are for sea and sky, km/h and mph are for land.

Millimeter per second measures distance in millimeters traveled in one second. Used for small-scale movements and precise measurements.

1 mm/s = 0.001 m/s = 0.0036 km/h = 0.06 m/min.

To m/s: ÷ 1,000. To cm/s: ÷ 10. To km/h: × 0.0036.

Vibration measurements (machinery typically 0.1–50 mm/s RMS), small motor speeds, precision linear actuators, and tape/film transport speeds.

Machinery vibration: >10 mm/s indicates problems. Seismic activity: 0.001–100 mm/s. CD/DVD read head: 1.2–1.4 mm/s linear velocity.

Confusing mm/s with cm/s (10× different) or m/s (1000× different).

1,000 mm/s = 1 m/s. Very common in vibration analysis. 10 mm/s RMS is a typical machinery vibration threshold.