Speed Calculator
Speed is one of the most familiar quantities in everyday life, yet it is easy to get tangled in units when distance and time do not line up neatly. This calculator removes that friction. Enter how far something travelled and how long it took, pick the units that match the numbers you actually have, and it returns the average speed in kilometres per hour, metres per second, miles per hour and knots all at once. There is no need to convert anything by hand, because the calculator first reduces your distance to metres and your time to seconds, works out the speed, and then expresses it in every common unit so you can read off whichever one you need. The idea behind it is simple: average speed is total distance divided by total time. That single relationship underpins everything from a runner pacing a race, to a driver estimating arrival, to a cyclist reviewing a ride, to a vessel logging a passage at sea. Because the result is an average, it smooths out the faster and slower stretches of a journey into one representative figure, which is exactly what you want when comparing trips or planning ahead. The unit choices cover most practical situations, including metres, kilometres, miles, feet, yards and nautical miles for distance, and seconds, minutes or hours for time. Type your values below and the answer updates instantly, with the supporting conversions shown alongside so you can see and trust where the number comes from rather than relying on a hidden calculation.
The formula
Average speed is the total distance divided by the total time taken. To keep the units consistent, the calculator converts your distance to metres and your time to seconds, then divides to get speed in metres per second, before expressing it in the other units.
speed = distance ÷ time
km/h = m/s × 3.6 · mph = m/s × 2.23694 · knots = m/s × 1.94384
Worked example
A trip covers 100 kilometres in 1.5 hours. That is 100,000 metres in 5,400 seconds, so the average speed is 100,000 ÷ 5,400 = 18.52 metres per second. Multiplying by 3.6 gives 66.67 kilometres per hour, which is also about 41.43 miles per hour and 36.00 knots.
Who this calculator is for
This calculator is for drivers, runners, cyclists, sailors, pilots, students and anyone who needs the average speed of a journey from a distance and a time.
What this calculator assumes
- The distance and time you enter cover the same journey.
- The result is the average speed over the whole trip, not the speed at any instant.
- Distance is converted to metres and time to seconds before dividing.
- Results are rounded for display.
Frequently asked questions
What is the formula for average speed?
Average speed equals distance divided by time. Divide the total distance by the total time, with both in compatible units.
How do I convert m/s to km/h?
Multiply metres per second by 3.6. For example, 10 m/s is 36 km/h.
How fast is one knot?
One knot is one nautical mile per hour, which is 1.852 km/h or about 0.514 m/s.
Is this average or instantaneous speed?
It is the average over the whole trip, total distance divided by total time, not the speed at a single moment.
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