Speed Converter
Convert speed between mph, km/h, m/s, knots, ft/s, and Mach instantly.
Common Speed References
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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This speed converter instantly translates between six common speed units: miles per hour, kilometers per hour, meters per second, knots, feet per second, and Mach number. It is useful for travel planning, aviation, physics homework, and comparing speeds across different measurement systems.
- Enter the speed value. Type any number into the speed field. The converter accepts whole numbers and decimals.
- Select the source unit. Choose the unit your original speed is measured in from the "From" dropdown. For example, select "mph" if your speed is in miles per hour.
- Select the target unit. Choose the unit you want to convert to from the "To" dropdown. The result updates instantly as you change either dropdown.
- Use the swap button. Click the arrows between the dropdowns to reverse the conversion direction without re-entering the value.
The result card shows the converted speed with a formula line underneath. Use Copy to paste the result into another app, or Share to send a link that pre-fills the same conversion for someone else. The reference table below the result lists common real-world speeds for quick comparison.
About Speed Conversion
Speed units vary by country and context. The United States and the United Kingdom use miles per hour for road travel, while most other countries use kilometers per hour. Aviation and maritime navigation rely on knots, which are nautical miles per hour. Scientific and engineering work typically uses meters per second, the SI standard. Mach number expresses speed relative to the speed of sound, which is approximately 343 meters per second (767 mph) at sea level under standard atmospheric conditions. This converter uses that standard value for all Mach calculations.
All conversions pass through meters per second as a base unit. The value is first converted to m/s, then from m/s to the target unit. This approach keeps the math simple and the rounding consistent across all unit pairs.
Frequently Asked Questions
How many km/h is 60 mph?
60 miles per hour equals approximately 96.56 kilometers per hour. The exact conversion factor is 1 mph = 1.60934 km/h. This is a common highway speed in the United States, equivalent to a typical speed limit on European motorways posted as 100 km/h.
What is the speed of sound in different units?
At sea level under standard atmospheric conditions, the speed of sound (Mach 1) is 343 meters per second, 1,235 kilometers per hour, 767 miles per hour, 1,125 feet per second, or approximately 667 knots. The actual speed of sound varies with temperature and altitude.
What are knots and why are they used in aviation?
A knot equals one nautical mile per hour, or approximately 1.151 mph (1.852 km/h). Knots are used in aviation and maritime navigation because nautical miles correspond directly to degrees of latitude, making it easy to measure distances on navigation charts. One nautical mile equals one minute of latitude.
How do I convert m/s to mph?
Multiply the meters per second value by 2.237 to get miles per hour. For example, 10 m/s equals 22.37 mph. Alternatively, multiply by 3.6 to get km/h first, then divide by 1.609 to convert to mph. This converter handles the calculation automatically for any speed value you enter.