Speed Conversion Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/5/2026
To convert a speed, it's brought to a common unit (meters per second) and then converted into the new unit. For example, 100 km/h is about 62.14 mph.
Explanation
Kilometers per hour (km/h) is the road-speed unit in most countries, while miles per hour (mph) remains the standard in the United States and the United Kingdom. Meters per second (m/s) is the reference unit in physics, often used in scientific calculations such as kinetic energy. The knot, finally, is the speed unit used in maritime and air navigation, equal to one nautical mile per hour (1.852 km/h). This calculator converts between these four units by going through meters per second as a pivot unit. For the kinetic energy associated with a given speed, see our kinetic energy calculator; for a runner's pace, our running pace calculator.
Example: converting 100 km/h to mph
Inputs
Value: 100. Starting unit: km/h. Target unit: mph.
Calculation
100 km/h × (1 ÷ 3.6) = 27.777... m/s. Dividing by 0.44704 (the mph factor) gives about 62.14 mph.
Result
100 km/h equals about 62.14 mph.
Frequently asked questions
Why divide by 3.6 to go from km/h to m/s?
Because there are 1,000 meters in a kilometer and 3,600 seconds in an hour: converting km/h to m/s amounts to multiplying by 1,000 then dividing by 3,600, which is the same as dividing directly by 3.6 (3,600 ÷ 1,000 = 3.6).
Is a knot the same as a mile per hour?
No, they're two different units despite their close values. The knot (1.852 km/h) is based on the nautical mile, while mph (1.609 km/h) is based on the statute (land) mile. The knot is reserved for maritime and air navigation, mph for road speeds in English-speaking countries.
What is meters per second used for in everyday life?
m/s is mainly used in scientific and technical contexts (meteorology for wind speed, physics, engineering), since it's the speed unit consistent with the International System of Units (meters and seconds). In everyday life, km/h or mph remain more intuitive.