Speed converter - mph, km/h, metres per second and knots

Speed is distance divided by time. A kilometre per hour describes how many kilometres are travelled in one hour; metres per second describes metres travelled in one second. To convert km/h to m/s, divide by 3.6. To convert m/s to km/h, multiply by 3.6. For miles per hour, 1 mph equals exactly 1.609344 km/h. Therefore, multiply mph by 1.609344 to get km/h, or divide km/h by 1.609344 to get mph.

A vehicle moving at 60 mph travels at about 96.56 km/h. A wind speed of 10 m/s equals 36 km/h or about 22.37 mph. The converter applies the unit relationship directly, so you can check values for driving, weather reports, sports or equipment specifications without doing the arithmetic by hand.

A knot is one nautical mile per hour. One international nautical mile is exactly 1,852 metres, so one knot equals 1.852 km/h or about 1.15078 mph. Knots are used for maritime and aviation speed because nautical distances relate naturally to latitude and longitude. Road signs generally use km/h or mph instead.

For example, a vessel travelling at 20 knots moves at 37.04 km/h, or about 23.02 mph. A common error is to treat knots and miles per hour as equivalent. They are close enough to look similar on a display but differ by about 15%. Select the correct source unit when reading a marine forecast, aircraft data or a navigation instrument.

Given a constant speed, estimated travel time is distance divided by speed. At 100 km/h, a 250 km journey takes 2.5 hours before breaks, traffic or delays. At 60 mph, a 150 mile journey also takes 2.5 hours under the same ideal assumption. Converting speed units can help compare a route estimate with a vehicle display or a speed limit stated in another system.

Actual journey time changes with congestion, stops, road conditions and legal limits. For a vehicle trip, plan using realistic average speed rather than the maximum shown on the dashboard. A speed conversion is a unit calculation only; it does not account for acceleration, elevation, wind resistance or road safety. Follow local speed limits and the instructions for your vehicle or activity.