Speed Converter: mph, km/h, m/s & Knots
A clear speed converter for road, science, aviation, and marine units, using exact length and time relationships with live equivalents.
Speed combines distance and time
Metres per second is the SI-derived speed unit. Kilometres per hour and miles per hour use the same time interval but different length units.
A knot is one nautical mile per hour. Because the international nautical mile is exactly 1,852 metres, one knot is exactly 1,852/3,600 metres per second.
Speed versus velocity
Speed is a magnitude and has no direction. Velocity includes direction, so this converter reports non-negative speed values rather than vectors.
Examples
Road speed
Input
100 km/h
Show result
Result
About 62.13712 mph
Marine speed
Input
10 kn
Show result
Result
18.52 km/h
Frequently Asked Questions
How fast is 100 km/h in mph?
100 kilometres per hour is approximately 62.13712 miles per hour.
What is one knot?
One knot is one nautical mile per hour, exactly 1.852 km/h.
Does this calculate journey time?
No. It converts a speed magnitude; use distance divided by average speed separately for a simplified time estimate.
References
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