Convert Beaufort Scale to Mile per Hour (Bft → mph)

Converting Beaufort to miles per hour 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 Beaufort

   Start with the number of Beaufort (Bft) you want to convert.
2. 2
   Multiply by 2.236936

   The conversion factor from Bft to mph is 2.236936. Multiply your value by this number.
3. 3
   Read the result in miles per hour

   The result is your value in miles per hour (mph).

Multiply the value in Beaufort by 2.236936. For the reverse direction, multiply by 0.44704.

• ✓Beaufort is empirical — conversion to m/s uses v = 0.836 × B^1.5.
• ✓Force 4 (moderate breeze) = 5.5–7.9 m/s.
• ✓Marine forecasts still use Beaufort alongside knots.

• ✗Treating Beaufort as a linear scale — it is a power relationship.
• ✗Converting Beaufort to km/h by multiplying — always use the empirical formula.
• ✗Using Beaufort for land winds — it was designed for sea conditions.

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

What is the Mile per Hour?

Miles per hour is the road-speed standard in the United States, the United Kingdom, and several Caribbean countries. American and British road signs, car speedometers, and weather reports use mph. Typical US speed limits are 25 mph (residential), 35–45 mph (urban arterials), 55–65 mph (rural highways), and 65–80 mph (interstates). The UK uses mph despite metric measurement elsewhere — a result of incomplete metrication. Mph derives from the mile (distance) and hour (time): 1 mph ≈ 1.609 km/h ≈ 0.447 m/s. World-class sprinters reach about 27 mph, professional baseball pitchers throw at 90–105 mph, and commercial airliners cruise at 550–600 mph. The unit relates to km/h (1 mph ≈ 1.609 km/h), m/s (1 mph ≈ 0.447 m/s), the knot (1 mph ≈ 0.869 kn), and ft/s (1 mph ≈ 1.467 fps).

• US and UK road speed limits
• US car speedometers
• US baseball pitch speeds