Driving in the UK means reading mph signs; pilots and sailors navigate in knots; physics problems demand m/s; and weather services report wind speeds in Beaufort or m/s. The speed converter switches between all common speed units instantly — with reference values for everyday life and professional use.
Step by Step: How to Use the Speed Converter
- Enter the source value: Type in the known speed — e.g. 130 (German motorway advisory limit) or 100 (speed limit in Austria).
- Select the source unit: km/h (European road traffic), mph (UK, USA), m/s (physics, meteorology), kn (knots, maritime/aviation), ft/s (imperial engineering).
- Read the result: All units are displayed simultaneously. Particularly useful when comparing European and American vehicle specification sheets.
- Find the Mach number (optional): The speed of sound at 20 °C is 343 m/s = 1,235 km/h = Mach 1. A supersonic aircraft at Mach 2 flies at 2,470 km/h.
- Compare with the Beaufort scale: Beaufort force 6 corresponds to 10.8–13.8 m/s = 39–49.7 km/h. The converter helps translate meteorological readings into familiar units.
Practical Examples
Example 1 – Driving in Great Britain: The urban speed limit is 30 mph; outside built-up areas 60 mph. Conversion: 60 mph × 1.60934 = 96.6 km/h. British rural roads therefore correspond to our typical country road speed.
Example 2 – Sailing in the North Sea: Weather forecast shows wind speed 25 knots. In km/h: 25 × 1.852 = 46.3 km/h. This equals Beaufort force 6 — manageable for experienced sailors, demanding for beginners.
Example 3 – Physics problem, braking distance: Vehicle brakes from 90 km/h. In m/s: 90 ÷ 3.6 = 25 m/s. Braking distance at a = −8 m/s²: v² / (2a) = 625 / 16 ≈ 39 m.
Speed Conversion: km/h, m/s, mph, Knots
Conversion factors: 1 km/h = 0.2778 m/s = 0.6214 mph = 0.5400 kn. 1 knot = 1.852 km/h. Motorway 130 km/h = 80.8 mph = 36.1 m/s = 70.2 kn. Speed of sound (20 °C): 343 m/s = 1,235 km/h = 667 kn.
Frequently Asked Questions (FAQ)
Why is one knot exactly 1.852 km/h?
One knot equals one nautical mile per hour. One nautical mile is exactly 1,852 m — corresponding to one arcminute of latitude on the Earth's meridian. This makes chart navigation direct: 60 knots = 1 degree of latitude per hour.
How do I quickly convert km/h to m/s in my head?
Rule of thumb: divide km/h by 3.6 to get m/s. Quick estimate: divide by 4 then multiply by 1.1. Example: 100 km/h ÷ 3.6 = 27.8 m/s; approximation: 100 ÷ 4 × 1.1 = 27.5 m/s.
What does Mach 1 mean and why does it vary?
Mach 1 is the local speed of sound and depends on temperature and medium. In dry air at 20 °C: 343 m/s. At sea level at 0 °C: 331 m/s. At cruising altitude (−56 °C): approximately 295 m/s — supersonic aircraft therefore have a lower Mach 1 threshold in the stratosphere.
