Speed, distance and time calculator

Formula

How it works

Average speed is the distance travelled divided by the time taken: v = d ÷ t. To convert, 1 m/s = 3.6 km/h ≈ 2.237 mph.

Worked example

The same calculation with the default values:

• Distance 1,000 m
• Time 125 s

1. v = 1,000 ÷ 125 = 8 m/s
2. 8 m/s × 3.6 = 28.8 km/h
3. 8 m/s ÷ 0.44704 = 17.89549 mph

Result: Speed (metres per second): 8 m/s · Speed (kilometres per hour): 28.8 km/h · Speed (miles per hour): 17.89549034 mph

Common mistakes

• Mixing distance units (km) with time units (seconds) without converting - the result's unit is only meaningful when distance and time use a matched pair (km and hours, or m and seconds).
• Using this average-speed formula for a trip with varying speed and assuming it represents the speed at every moment - it only gives the overall average over the whole distance and time.
• Confusing average speed with average velocity - speed uses total distance travelled, while velocity uses straight-line displacement; they're equal only for motion in one constant direction.