Average Speed Calculator (Multiple Legs)
How do you calculate average speed for a trip with several legs? Enter each leg's distance with either its speed or its time. Average speed is total distance divided by total time, not the mean of the speeds, and the calculator shows both so you can see the gap. For a single speed and time use the velocity calculator, and for fuel and cost use the trip cost calculator.
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Formula
average speed = total distance ÷ total time
Each leg's time is distance ÷ speed (or the time you enter, in minutes ÷ 60). The simple average of speeds is shown only to expose the trap: for equal distances the right answer is the harmonic mean, n ÷ (1/v1 + 1/v2 + ...).
Worked example
60 km at 30 km/h takes 2 h; 60 km at 60 km/h takes 1 h. Total 120 km in 3 h gives 40 km/h. The simple average, (30 + 60) ÷ 2 = 45, is 5 too high.
Round trip: 100 miles at 60 mph (1.667 h) and 100 miles back at 40 mph (2.5 h). Total 200 miles in 4.167 h is 48 mph, against a simple average of 50.
Use this when
You drove or will drive in stages at different speeds and want one figure for the whole trip: planning an arrival time, checking a journey log, or answering a homework question about a round trip. Use the time mode when you know how long each leg took rather than how fast you went.
Typical values
Typical average speeds are roughly 20 to 40 km/h in city traffic and roughly 80 to 100 km/h on open highway, but the speed limit, stops and congestion decide the real number.
How it differs from nearby pages
The velocity calculator handles one distance and one time. The speed converter changes units, for example mph to km/h. This page combines several legs. The range on a tank calculator uses fuel, not time.
Common mistakes
- Averaging the speeds instead of totalling distance and time.
- Mixing distance units between legs. Use one unit and the answer is in that unit per hour.
- Entering a time in hours in the time mode, which expects minutes.
- Leaving out stops: the time spent stopped counts in the total time.
Frequently asked questions
How do you calculate average speed?
Divide the total distance by the total time. Driving 100 km in 90 minutes and then 50 km in 30 minutes is 150 km in 2 hours, so 75 km/h.
Why is the average of two speeds not the average speed?
You spend more time at the slow speed. Driving 60 km at 30 and then 60 km at 60 takes 2 + 1 = 3 hours for 120 km, so the average is 40, not (30 + 60) ÷ 2 = 45.
What is the harmonic mean trap?
When the legs cover equal distances, the true average speed is the harmonic mean of the speeds: n ÷ (1/v1 + 1/v2 + ...). It is always lower than the ordinary mean unless all speeds are equal. Equal times are the only case where the ordinary mean is right.
Does this work in miles or kilometres?
Yes. Use the same distance unit everywhere and the result is in that unit per hour. Time-based legs are entered in minutes.
What is the average speed of a round trip at 60 and 40 mph?
Take two legs of 100 miles at 60 mph and 40 mph. The times are 1.667 h and 2.5 h, so 200 miles takes 4.167 h and the average is 48 mph. The simple average of 50 mph is 2 too high.
How do I calculate average speed in km/h from time in minutes?
Switch to the distance and time mode and enter minutes. A 15 km leg in 20 minutes is 0.333 h, so the average is 45 km/h. Two legs of 100 km in 90 minutes and 50 km in 30 minutes give 150 km in 2 h, or 75 km/h.
How do I average speed over three or more legs?
Add up every distance and every time, then divide. The calculator takes up to five legs and skips any you leave at zero. It also reports the simple average of the leg speeds, so you can see how far that shortcut is from the true value.