Convert meters per second to kilometers per hour

Speed limits are posted in miles per hour in the UK and US, and in km/h almost everywhere else, so a hire car's speedometer may show both. 1 mph is 1.609 km/h: 30 mph is 48 km/h, 50 mph 80 km/h and 70 mph, the British motorway limit, 113 km/h. Going the other way, 50 km/h is 31 mph and 130 km/h, the French motorway limit, is 81 mph. A quick rule: mph × 8 ÷ 5 = km/h.

The SI unit of speed converts simply: 1 m/s is exactly 3.6 km/h, about 2.24 mph or 1.94 knots. A brisk walk is 1.5 m/s, a sprinter peaks at 12, sound travels at 343 m/s and a satellite in low orbit at 7.7 km/s. Weather services in the Nordic countries, Russia, Japan and China give wind speeds in m/s, where a strong breeze (Beaufort 6) is 11–14 m/s and a storm starts at 25; lifts are rated in m/s too, the fastest reaching 20. Metres per minute is the unit of conveyor belts and machining feeds.