How this calculator works
- Step 1Speedd ÷ tFrom distance and time.
- Step 2Distancev × tFrom speed and time.
- Step 3Timed ÷ vFrom distance and speed.
Average speed is the total distance divided by the total time. The calculator converts everything to metres and seconds, solves, and converts back to the units you choose.
Worked example: a commuter train
- Average speed
distance ÷ time
- Distance80 × 1,609.344 m128,747.52 m
- Time105 × 60 s6,300 s
- Speed128,747.52 ÷ 6,30020.436114 m/s
OpenStax College Physics works this out for a round trip of 80 miles and rounds the answer to 20 m/s.
Distance or time
- How far?67.5 km45 minutes at 90 km/h.
- How long?6 hours300 km at 50 km/h.
Read the result
The headline is the quantity you chose, in the unit you picked; the table shows the speed in km/h, m/s and mph.
150 km in 2.5 hours averages 60 km/h.
Assumptions and limits
- Average speedOver the whole trip, not the top speed.
- Exact units1 mile = 1,609.344 m; 1 m/s = 3.6 km/h.
- Stops countInclude stops in the time for an overall average.
Related motion tools
Average speed is distance over time. Changing speed and running pace have their own tools.
For constant acceleration and stopping distance, use the kinematics calculator. Runners can use the pace calculator, and drivers the fuel cost calculator for a trip’s cost.
Common mistakes
Mistake: Entering 1 hour 30 minutes as 1.3 hours.
Instead: Use 1.5 hours or 90 minutes.
Mistake: Averaging two speeds for an out-and-back trip.
Instead: Divide the total distance by the total time.
Checking the method
Every golden case is rechecked with exact fractions and direct unit factors, and the OpenStax train example is reproduced.
An independent script converts each value straight into the answer’s unit, without going through metres per second.
Read how we test our calculators, or browse more maths calculators.