Speed Converter
Convert a speed between km/h, mph, knots and metres per second - perfect for reading a foreign speed limit or a boat or wind report.
About the Speed Converter
This tool converts a speed between metres per second, kilometres per hour, miles per hour, knots and feet per second. It covers the units you meet on road signs, weather reports, fitness trackers and marine or aviation charts.
How to use it
- Type the speed you know into its field, such as a speed limit in km/h.
- Read the equivalent in mph, knots or m/s.
- Enter values in any unit to convert the other way, for example a wind speed given in knots.
This is useful when driving abroad and reading a limit in the unfamiliar unit, or when comparing a sailing or wind report in knots to a road speed. A knot is one nautical mile per hour, which equals exactly 1.852 km/h. A quick mental check: km/h is about 0.621 of mph, so 100 km/h is roughly 62 mph. The converter runs entirely in your browser, so the values you enter are never uploaded.
Frequently asked questions
How do I convert km/h to mph?
Multiply the km/h value by 0.621371. For example, 100 km/h is about 62.1 mph. To go the other way, multiply mph by 1.60934.
What is a knot in km/h?
One knot equals exactly 1.852 km/h, which is one nautical mile per hour. That makes one knot about 1.151 mph.
How do I convert metres per second to km/h?
Multiply metres per second by 3.6. So 10 m/s equals 36 km/h, because there are 3600 seconds in an hour and 1000 metres in a kilometre.
Why are boat and aircraft speeds measured in knots?
Knots tie directly to nautical miles, which are based on minutes of latitude. That makes navigation and chart work simpler at sea and in the air.