Convert Mach to Beaufort Scale (Ma → Bft)

Converting Mach to Beaufort is straightforward: multiply by the conversion factor. Follow these three steps to do it by hand or in your head.

1. 1
   Take your value in Mach

   Start with the number of Mach (Ma) you want to convert.
2. 2
   Multiply by 340.29

   The conversion factor from Ma to Bft is 340.29. Multiply your value by this number.
3. 3
   Read the result in Beaufort

   The result is your value in Beaufort (Bft).

Multiply the value in Mach by 340.29. For the reverse direction, multiply by 0.002939.

• ✓Mach 1 = ~1225 km/h at sea level, standard conditions.
• ✓Local speed of sound decreases with altitude (colder air) — true Mach value varies.
• ✓Mach 0.8+ is "transonic"; Mach 1+ supersonic; Mach 5+ hypersonic.

• ✗Assuming Mach 1 is a fixed speed — depends on altitude and temperature.
• ✗Multiplying Mach values as simple ratios across altitudes.
• ✗Using Mach for subsonic everyday speeds — not practical.

What is the Mach?

Mach is a dimensionless speed ratio comparing an object's speed to the local speed of sound (about 343 m/s in air at sea level, varying with altitude and temperature). Named after Austrian physicist Ernst Mach (1838–1916), who pioneered supersonic photography, the unit became standard with high-speed aviation. Mach 1 = sound speed; Mach 2 = twice sound speed. The Concorde cruised at Mach 2.04, the SR-71 Blackbird reached Mach 3.3, and modern commercial jets cruise at Mach 0.78–0.85 (subsonic). 'Breaking the sound barrier' (first achieved by Chuck Yeager in 1947) means crossing Mach 1 in horizontal flight. Hypersonic missiles operate above Mach 5. Mach is essential in aerodynamics because shock waves, drag, and heating all depend on the relationship between vehicle speed and sound speed. At sea level: Mach 1 ≈ 1,235 km/h ≈ 767 mph ≈ 343 m/s.

• Military and supersonic-aircraft speeds
• Aerospace engineering
• Hypersonic missile specifications

What is the Beaufort Scale?

The Beaufort scale is an empirical wind-force scale ranging from 0 (calm) to 12 (hurricane), developed in 1805 by British Royal Navy Admiral Francis Beaufort. Originally designed for ships at sea, the scale was based on observed effects: 'How much sail can my ship safely carry?' Modern versions describe both observed effects on land and sea and corresponding wind-speed ranges. Force 0 is dead calm (under 1 km/h), Force 6 is 'strong breeze' (39–49 km/h, large branches in motion), Force 10 is a 'whole storm' (89–102 km/h), and Force 12 is hurricane (over 118 km/h). The conversion to numeric speeds follows v = 0.836 × Bft^1.5 m/s. Sailors, meteorologists, and shipping forecasts still use the Beaufort scale because its descriptive nature is intuitive: 'Force 8 gale' immediately conveys conditions to anyone familiar with the scale.

• Marine weather forecasts
• Sailing and offshore navigation
• Historical weather records