Calculate average speed from distance and time
Average speed is the total distance travelled divided by the total time taken. It does not tell you the speed at any specific moment — only the overall rate across the entire journey.
Speed = Distance ÷ Time
For example, travelling 240 km in 3 hours gives an average speed of 80 km/h. The same formula works for any units — miles and hours give mph, metres and seconds give m/s.
The relationship between speed, distance, and time can be rearranged to find any one value when the other two are known:
| To find | Formula | Example |
|---|---|---|
| Speed | Distance ÷ Time | 150 km ÷ 2 h = 75 km/h |
| Distance | Speed × Time | 80 km/h × 3 h = 240 km |
| Time | Distance ÷ Speed | 300 km ÷ 60 km/h = 5 h |
| From | To | Multiply by |
|---|---|---|
| km/h | mph | 0.6214 |
| mph | km/h | 1.6093 |
| m/s | km/h | 3.6 |
| km/h | m/s | 0.2778 |
| knots | km/h | 1.852 |
Average speed smooths out all the variation in a journey. A car that travels 100 km in 1 hour has an average speed of 100 km/h — but it may have stopped at traffic lights, accelerated on motorways, and crawled through town. The speedometer shows instantaneous speed; this calculator gives you the average.
This distinction matters in sports. A marathon runner finishing 42.195 km in 3 hours has an average speed of about 14 km/h, but their pace varied throughout the race. A cyclist's average speed on a stage race includes climbs, descents, and flat sections with very different instantaneous speeds.
| Reference | Speed |
|---|---|
| Walking pace | ~5 km/h |
| Cycling (leisure) | ~15 km/h |
| City traffic | ~30 km/h |
| Motorway / highway | 100–130 km/h |
| Commercial aircraft | ~900 km/h |
| Speed of sound | ~1,235 km/h |
Divide the total distance by the total time. If you drove 360 km in 4 hours, your average speed was 360 ÷ 4 = 90 km/h.
Divide distance by speed. A 450 km journey at 90 km/h takes 450 ÷ 90 = 5 hours.
Multiply km/h by 0.6214. For example, 100 km/h × 0.6214 = 62.14 mph. To go the other way, multiply mph by 1.6093.
Speed is a scalar — it has magnitude only (how fast). Velocity is a vector — it has both magnitude and direction (how fast and in which direction). A car driving at 60 km/h north has the same speed as one driving at 60 km/h south, but opposite velocities.
GPS speed is based on position changes over time and is close to instantaneous speed. This calculator gives average speed for the entire trip. If you made stops, your GPS speed during the trip was higher than your average speed for the total journey.