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Mihsaba›Mach Number Calculator

Mach Number Calculator

Calculate Mach number from object or flow speed and local speed of sound, with an approximate flow-regime label and speed in km/h.

Regime boundaries are approximate and application-dependent; use the correct local speed of sound.

How to use

Mach number is the ratio of motion speed to the local speed of sound. The same physical speed can therefore produce a different Mach number when local acoustic speed changes.

  1. Enter object or flow speed.
  2. Enter local speed of sound.
  3. Calculate Mach number.
  4. Treat the regime label as approximate guidance.

How it is calculated

M=v/a

Example

A speed of 250 m/s with a 343 m/s local speed of sound gives M≈0.729, subsonic under the approximate boundaries used here.

Important notes

Speed of sound is not constant. The 0.8, 1.2 and 5 regime boundaries used here are approximate, not universal definitions.

Frequently asked questions

Does Mach have units?

No; it is a ratio of two speeds in the same units.

Is 343 m/s always the speed of sound?

No. Use the local value for the actual medium and conditions.

Why is there a transonic band?

Near Mach 1, different regions of flow can locally be subsonic or supersonic.