Knot to Millimeter per Hour

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 hour measures extremely slow movements in millimeters over an hour. Used for minute geological and material changes.

1 mm/h = 0.001 m/h = 0.0000001 km/h = 0.000000278 m/s.

To m/s: ÷ 3,600,000. To cm/h: ÷ 10. To m/h: ÷ 1,000.

Cave formation rates (stalactite/stalagmite growth), extremely slow material creep, and long-term geological monitoring.

Stalactite growth: 0.1–1 mm/h in active caves. Human hair growth: ~0.015 mm/h. Fingernail growth: ~0.004 mm/h.

Using for anything except the slowest processes. Confusing with mm/min (60× faster).

1,000 mm/h = 1 m/h. Extremely specialized unit. Think geological time scales.