Millimeter per Hour to Millimeter per Second

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.

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.