How to use the speed converter
- 1 Type the value you want to convert.
- 2 Choose the unit to convert from and the unit to convert to.
- 3 Press ⇄ to swap the two units.
- 4 Read the result, and see the same speed in every other unit in the table below.
Speed units in everyday life
Road signs use km/h or mph, weather services use km/h, mph, m/s or knots, and physics uses m/s. Divide km/h by 3.6 for m/s, and multiply mph by 1.609 for km/h. For distances, use Miles to KM or KM to Miles.
- Speedometers are usually a little optimistic; GPS speed is closer to true.
- Wind of 50 km/h is about 27 knots, a strong breeze at sea.
- To get a running pace, divide 60 by the speed in km/h.
Features
Five speed units
km/h, mph, m/s, knots and ft/s.
Exact factors
1 mph = 1.609344 km/h and 1 knot = 1.852 km/h exactly.
All units at once
See the speed in every unit in the table.
When to use it
Driving abroad
A 100 km/h limit is 62 mph and 70 mph is 113 km/h. For distances, use Miles to KM.
Weather and wind
Forecasts may give wind in km/h, mph, m/s or knots. A 20 knot wind is 37 km/h.
Running and cycling
A 12 km/h running speed is 7.46 mph, a pace of 5 minutes per kilometre.
Science homework
Physics problems usually need metres per second; divide km/h by 3.6.
Related Unit tasks
Frequently asked questions
How do I convert km/h to mph?
Divide by 1.609344, or multiply by 0.6214. 80 km/h is 49.7 mph.
How do I convert mph to km/h?
Multiply by 1.609344. 30 mph is 48.3 km/h.
How do I convert km/h to m/s?
Divide by 3.6. 72 km/h is 20 m/s.
What is a knot?
One nautical mile per hour, exactly 1.852 km/h or about 1.15 mph. It is used at sea and in aviation.
How fast is the speed of sound?
About 343 m/s, or 1,235 km/h, in dry air at 20 °C. It changes with temperature, so Mach numbers are not fixed speeds.
What is a fast walking speed?
About 5 to 6 km/h, or 3 to 3.7 mph, for most adults.
How do I turn speed into pace?
Divide 60 by the speed in km/h to get minutes per kilometre. 10 km/h is a pace of 6 minutes per kilometre.
Why do aircraft use knots?
Navigation uses nautical miles because one nautical mile matches one minute of latitude, which makes chart work easier.
How fast is 1 m/s?
3.6 km/h or 2.24 mph, a slow walk.
Are the conversions exact?
Yes. The mile, the nautical mile and the hour are defined exactly, so only the displayed decimals are rounded.
Which speed unit do weather forecasts use?
It varies by country and service. Many forecasts use kilometres per hour, the United Kingdom and United States often use miles per hour, aviation and shipping use knots, and scientists use metres per second.
Why do speed limits differ between countries?
Each country sets its own limits for its roads, and they are written in the local unit. Motorway limits are often around one hundred and twenty kilometres per hour or seventy miles per hour, but always follow the signs.
How do I work out travel time from speed?
Divide the distance by the speed. A journey of one hundred and twenty kilometres at an average of eighty kilometres per hour takes one and a half hours, before stops and traffic.
Built and reviewed by Hamza Farooq, founder and lead developer
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