What Is the Average Speed Calculator?
This calculator finds the true average speed of a journey made up of two legs. A common mistake is to average the two individual speeds — but that only works if both legs take the same amount of time. The correct method is to divide the total distance by the total time. This tool does exactly that for any consistent units (km/h, mph, m/s — just keep distance and time units matched).
How to Use It
Enter the distance and time for the first leg, then the distance and time for the second leg. Times are entered in hours. Click calculate to get your overall average speed, plus the combined distance and time. You can use it for road trips, running splits, cycling segments, or any two-part movement.
The Formula Explained
The average speed is:
$$\text{Average Speed} = \frac{\text{Distance 1} + \text{Distance 2}}{\text{Time 1 (h)} + \text{Time 2 (h)}}$$
Here \(d_1\) and \(d_2\) are the distances of each leg and \(t_1\) and \(t_2\) are the times. Adding the distances gives the total distance traveled; adding the times gives the total elapsed time. Dividing one by the other yields the speed that, held constant, would cover the same distance in the same time.
Worked Example
Suppose you drive 60 km in 1 hour, then 120 km in 2 hours. Total distance = \(60 + 120 = 180\) km. Total time = \(1 + 2 = 3\) hours. Average speed = $$180 \div 3 = 60 \text{ km/h}$$ Notice this is not the simple average of 60 km/h and 60 km/h here, but the method matters when the speeds differ.
FAQ
Why not just average the two speeds? Averaging speeds ignores how long you spent at each speed. Total distance over total time always gives the correct answer.
What units should I use? Any units work as long as distance and time are consistent — distances in miles with times in hours give mph.
Can I use it for more than two legs? This version handles two legs; for more, sum all distances and all times and divide.
