Speed Converter

A Speed Converter changes a rate of motion from one unit to another. It is useful for travel notes, running and cycling comparisons, weather data, classroom problems, engineering examples, and spreadsheet cleanup.

Speed is distance over time, so the unit label matters. Miles per hour, kilometers per hour, meters per second, feet per second, and knots all describe motion, but they fit different contexts.

Enter a speed value, choose the source unit, then choose the target unit. The result updates automatically when the amount or either unit changes.

The current Speed Converter code converts through meters per second as the shared base unit. It multiplies by the source unit rate, divides by the target unit rate, and shows seven significant digits.

The unit list includes common road, metric, imperial, knot, sound-speed, light-speed, and Mach references. For Mach, use the listed reference carefully because real speed of sound varies with conditions.

If a speed limit is 60 mph, mph to kmh gives about 96.5606 km/h. If a road sign says 100 km/h, kmh to mph gives about 62.1371 mph. If a physics problem gives 10 m/s, m/s to mph gives about 22.3694 mph.

For marine speed, 20 knots equals about 23.0156 mph. For a classroom Mach reference at 20 C, Mach 1 is listed as 343.6 m/s in the current unit data.

These common speed conversions match the searches people use most often.

Speed conversion is useful when the same movement is described for different audiences.