Average trip speed: add the times of both legs
Use total distance and elapsed time when two parts of a journey have different speeds.
Method
For each leg, time equals distance divided by speed. Add all distances and all times, then divide total distance by total time. Do not normally average the listed speeds: equal distances can take different amounts of time. Use one distance unit and its matching time unit. Include stops if you want the average for the entire journey; leave them out only when explicitly calculating moving speed.
Worked example
Travel 120 KM at 60 KM/h, then 120 KM at 120 KM/h. The legs take two hours and one hour. The journey average is 240 ÷ 3 = 80 KM/h, not (60 + 120) ÷ 2 = 90 KM/h. Add a 30-minute stop and the elapsed-time average becomes 240 ÷ 3.5 ≈ 68.57 KM/h. These examples assume constant speed within each leg.
What to check
The Speed converter helps normalize KM/h, mph and m/s; it does not replace the distance/time calculation for this example. Record elapsed time consistently, especially for an overnight trip. Averaging speeds directly works for equal time periods, not generally for equal distances. A journey average says nothing about the highest speed reached and should not be treated as a driving target.