Speed Converter: km/h, mph, m/s, and ft/s
Speed units appear in vehicle displays, science problems, sports, and travel. Enter a speed, choose the source unit, and convert it into the unit you need.
How to use this tool
- Enter the speed as a number.
- Select km/h, mph, m/s, or ft/s as the source.
- Choose the desired target unit.
- Click Convert and check the displayed result.
Options explained
The calculation converts through a standard meter-per-second base factor. The converter handles unit changes only; it does not account for local speed limits or road conditions.
Accuracy and limitations
Use an official instrument for driving, aviation, or safety decisions. Rounded online conversions are not a substitute for calibrated equipment.
The units this converter knows
The converter handles ten units: metres per second, kilometres per hour, miles per hour, feet per second, knots, nautical miles per minute, nautical miles per day, kilometres per second, centimetres per second and Mach. A knot is one nautical mile per hour, which is 1.852 km/h, and it is the unit used for ships and aircraft. Mach compares a speed with the speed of sound, and the tool uses 340.29 m/s, the value at sea level.
Worked examples
A speed of 100 km/h is about 62.14 mph, and 60 mph is about 96.56 km/h. To change km/h into m/s divide by 3.6, so 36 km/h is 10 m/s, and to go back multiply by 3.6. A ship moving at 20 knots travels at about 37.04 km/h. One Mach at sea level is 340.29 m/s, or about 1,225 km/h. Check one of these in the tool first so you see how each pair of units behaves.
Using the result sensibly
Road signs differ between countries, some in kilometres per hour and some in miles per hour, so check the unit on a sign or a car before you drive in a new country. The speed of sound changes with temperature and height, so Mach in this tool is only exact at sea level. Results are rounded for display, and they are not meant for aviation, navigation or safety decisions.
Frequently asked questions
How fast is one knot in km/h?
One knot is one nautical mile per hour, which is 1.852 km/h or about 1.151 mph. Ships and aircraft use knots.
How do I convert km/h to m/s?
Divide the speed in km/h by 3.6. For example 72 km/h is 20 m/s.
Is one Mach always the same speed?
No. It depends on temperature and altitude. This tool uses the sea-level value of 340.29 m/s.
Which units do ships and aircraft use?
Both commonly use knots, which are nautical miles per hour. One knot is 1.852 km/h.
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