Mach (SI Standard) to Millimeter per Second

Mach (SI standard) uses the speed of sound at 0°C and 1 atm (295.0464 m/s) as the reference, based on SI standard conditions.

Mach (SI) = velocity / 295.0464 m/s. At 0°C, 1 atm: speed of sound ≈ 295 m/s (colder than 20°C).

To m/s (at 0°C): × 295.05. To km/h (at 0°C): × 1,062. To Mach (20°C): × 0.859.

Rarely used in practice. Theoretical aerodynamics at SI conditions, some scientific papers.

Mach 1 (SI) = 295 m/s, while Mach 1 (20°C) = 343.6 m/s. Same Mach number, different actual speeds depending on definition.

Assuming all Mach numbers use the same reference — they don't. Always check temperature and pressure conditions.

Rarely encountered. Mach 1 (SI) = 295 m/s at 0°C. Standard aviation Mach uses different conditions. Know your reference!

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.