Average Speed Calculator

What the average speed calculator does

You covered a certain distance, it took a certain amount of time, and you want to know how fast you were going on average. That is the job here. You give it the distance and the time, and it gives you your average speed three ways at once, in meters per second, miles per hour, and kilometers per hour, so you do not have to convert anything yourself.

It is not just for cars. The distance box takes miles, kilometers, yards, feet, or meters, so the same tool works for a road trip, a track run, a bike ride, or a swim.

How to use it

One distance, then your time split into three boxes.

1. Distance. How far you went, and pick the unit next to it: miles, kilometers, yards, feet, or meters.
2. Hours, Minutes, Seconds. How long it took, split across the three boxes. For a 90 minute trip you would put 1 in hours and 30 in minutes. Leave a box blank and it counts as zero.

Press Calculate to see your speed in all three units, or Reset to clear the boxes.

How average speed is worked out

The whole thing is one division. Average speed is the distance you covered divided by the time it took:

Average speed = distance ÷ time

To keep the three output units honest, the tool first turns your distance into meters and your time into seconds, works out the speed in meters per second, then converts that into miles per hour and kilometers per hour. So whatever units you enter, the three answers always agree with each other.

An example with real numbers

Say you drove 250 miles and it took 5 hours.

• Average speed = 250 ÷ 5 = 50 miles per hour
• The same speed is about 80.5 km/h
• And about 22.35 meters per second

So you held 50 mph on average across the whole trip. Notice that word, average. It does not mean you sat on exactly 50 the entire way. It means that if you had driven at a steady 50 the whole time, you would have covered the same 250 miles in the same 5 hours.

Why it is not the average of two speeds

This is the part that catches almost everyone, so it is worth doing slowly. Say you drive to a town 120 miles away at 60 mph, then drive the same 120 miles home at 40 mph. What was your average speed for the round trip?

The tempting answer is to add 60 and 40 and halve it, which gives 50. That answer is wrong. Here is why. The trip out at 60 mph took 2 hours. The trip back at 40 mph took 3 hours. So you spent more time going slowly than going fast. Now use the real formula:

• Total distance = 120 + 120 = 240 miles
• Total time = 2 + 3 = 5 hours
• Average speed = 240 ÷ 5 = 48 mph

So the real answer is 48, not 50. The slower leg eats up more of the clock, so it drags the average down further than the faster leg lifts it. The lesson is simple: to get an honest average, always go back to total distance divided by total time, and never just average the speeds.

Average speed versus average velocity

One more thing that trips people up in a physics class. Average speed and average velocity are not the same. Speed only cares how far you travelled. Velocity cares where you ended up, in a straight line from the start. On that round trip above, your average speed was 48 mph, but your average velocity was zero, because you finished exactly where you began, so your straight-line distance from start to finish was nothing. This calculator gives you speed, the honest measure of how much ground you actually covered.

Using it to pace a run or a ride

Because the distance box goes down to meters and the speed comes back in meters per second, this works nicely for training, not just driving. Run 5 km and punch in your time, and the meters-per-second figure is your pace in the units track athletes actually use. Do the same after a few runs and you can watch whether you are getting quicker over the same distance, which is a cleaner measure of progress than how you felt on the day.

Questions people ask

What is the formula for average speed?

Total distance divided by total time. That single formula always works, no matter how many times your speed changed along the way.

Why can I not just average my two speeds on a round trip?

Because you spend more time at the slower speed, so it weighs more heavily. Drive out at 60 and back at 40 over the same distance and the real average is 48, not 50. Always use total distance over total time.

Should I include stops in the time?

That depends on what you want. Include the time you were stopped and you get your overall trip average, which is the realistic one for planning. Count only the time you were actually moving and you get your moving average instead.

Which speed unit should I read?

Whichever suits the job. Miles per hour or kilometers per hour for driving, depending on your country, and meters per second for running, physics, or anything scientific, since that is the standard unit of speed.

References

1. National Institute of Standards and Technology (NIST), Special Publication 811: Guide for the Use of the International System of Units (SI). https://www.nist.gov/pml/special-publication-811
2. Bureau International des Poids et Mesures (BIPM), The International System of Units (SI Brochure, 9th edition), on the metre per second as the SI unit of speed. https://www.bipm.org/en/publications/si-brochure