Speed Converter
Convert between speed units instantly. Transform miles per hour to kilometers per hour, knots to mph, and more. Essential for driving, aviation, marine navigation, and physics calculations.
Reviewed by the SparkCalc editorial team
How We Calculate This
All conversions use meters per second as the base unit. 1 mph = 0.44704 m/s, 1 km/h = 0.27778 m/s, 1 knot = 0.51444 m/s, 1 ft/s = 0.3048 m/s, Mach 1 = 343 m/s.
Sources: BIPM — The International System of Units (SI Brochure) · NIST — Special Publication 330: The International System of Units (SI) · NIST — Guide to the SI, Appendix B.8: Factors for Units Listed Alphabetically
Frequently Asked Questions
How do I convert mph to km/h?
Multiply mph by 1.609 to get km/h. For example, 60 mph = 60 × 1.609 = 96.6 km/h. To convert km/h to mph, divide by 1.609.
What is a knot?
1 knot equals 1 nautical mile per hour, which is 1.852 km/h or 1.151 mph. Knots are used in maritime and aviation navigation.
What is Mach speed?
Mach 1 is the speed of sound, approximately 343 m/s or 767 mph at sea level. Mach 2 is twice the speed of sound, etc. The exact value varies with temperature and altitude.
How fast is the speed of light?
The speed of light is approximately 299,792,458 m/s or about 671 million mph. This is often denoted as "c" in physics.
Related Calculators
You might also find these calculators helpful: Pace Calculator, and Fuel Cost Calculator.
Embed this calculator
Add this free calculator to your own website. Copy the code below and paste it into your page’s HTML — it’s responsive and resizes to fit.