Speed combines distance and time
The kilometer per hour and mile per hour use the same time interval, while meters per second changes both units. A knot uses a nautical mile per hour, so it is not interchangeable with mph. This tool converts the speed supplied; it does not measure speed or calculate acceleration.
Worked examples
Road sign: 100 km/h ÷ 1.609344 ≈ 62.1371192237 mph. Follow the posted local limit rather than rounding it up.
Science exercise: 36 km/h ÷ 3.6 = 10 m/s. At a constant 10 m/s, an object covers 50 m in 5 seconds.
Marine forecast: 20 knots × 1.852 = 37.04 km/h. This converts the stated wind speed and does not account for gusts.
Formula / Calculation Method
Target speed = input × source factor in m/s ÷ target factor in m/s.
1 km/h = 1/3.6 m/s; 1 mph = 0.44704 m/s; 1 knot = 1.852 km/h.
1 km/h = 1/3.6 m/s; 1 mph = 0.44704 m/s; 1 knot = 1.852 km/h.
How to Use This Tool
- Enter a number using a period for decimals, for example 2.5.
- Choose the From and To units. The result and reference table update as you type.
- Use Swap to reverse the units while keeping your entered value, or Copy Result to save the conversion.
Common Use Cases
Understand speed units on a trip
Compare wind speeds in knots and km/h
Check distance-over-time calculations
Speed is different from pace
A running pace such as 5 minutes per kilometer is time per distance. It must be inverted to get speed: 60 ÷ 5 = 12 km/h. Enter 12 km/h here to compare it with mph; entering 5 would mean a different speed.
These are scalar unit conversions. They do not include direction, a vehicle's speedometer error, changing speeds, traffic, or current. To estimate travel time, divide distance by speed only after choosing compatible units and acknowledging any stops.