Speed Converter
Convert common speed units. Processing for supported tools happens locally in your browser.
About Speed Converter
Use this browser-based utility for everyday tasks. Review output before relying on it and retain a copy of important originals.
Read the Speed Converter guide →About Speed Converter
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 Speed Converter
- 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.
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.
More Converters tools
- Unit Converter: Convert common measurement units
- Length Converter: Convert between units of length
- Weight Converter: Convert between units of mass
- Temperature Converter: Convert Celsius, Fahrenheit and Kelvin
- Area Converter: Convert common area units
- Volume Converter: Convert common volume units
Want more detail, examples and answers to common questions? Read the Speed Converter guide.