How to Convert Speed Units: mph, km/h, m/s and Knots
Different fields settled on different speed units - mph for US road signs, km/h almost everywhere else, knots for aviation and sailing, m/s for physics. Converting between them is simple arithmetic once you know the ratios, and even simpler with a calculator that does all five at once.
Common speed unit conversions
| From | To | Multiply by |
|---|---|---|
| mph | km/h | 1.60934 |
| km/h | mph | 0.62137 |
| mph | m/s | 0.44704 |
| knots | mph | 1.15078 |
| knots | km/h | 1.852 |
| m/s | km/h | 3.6 |
Why knots are still used in aviation and sailing
A knot is one nautical mile per hour, and a nautical mile is defined from the Earth's own geometry - one minute of latitude - which makes it directly useful for navigation calculations in a way mph or km/h are not. That practical link to navigation is why aviation and maritime contexts have kept knots as the standard speed unit even as most everyday measurement moved to metric or imperial road units.
When you actually need to convert speed units
- Driving or cycling in a country that posts speed limits in a different unit than your speedometer shows.
- Reading a weather report or wind forecast that lists wind speed in knots or km/h.
- Physics or engineering problems that specify speed in m/s.
How to convert speed units online for free
- Open the Speed Converter.
- Type a speed in mph, km/h, m/s, knots, or ft/s.
- See it converted across all five units at once, instantly.
Questions
Frequently asked
How many km/h is 1 mph?
1 mph equals approximately 1.60934 km/h.
What is a knot in mph?
One knot equals approximately 1.15078 mph.
Is this speed converter free?
Yes, completely free to use with no limits and no sign-up.
How precise are the conversions?
They use standard, widely accepted conversion factors, shown to three decimal places for practical accuracy.