Quick brief
What to know before you calculate
A short read on the assumptions, trade-offs and definitions that shape the answer.
- Speed equals distance divided by time.
- Distance equals speed multiplied by time.
- Units must match before the result is meaningful.
The three linked formulas
Speed, distance and time are three ways of describing the same movement. Speed equals distance divided by time. Distance equals speed multiplied by time. Time equals distance divided by speed.
Choose the right unit pair
Miles per hour needs miles and hours. Kilometres per hour needs kilometres and hours. Metres per second needs metres and seconds. Mixing miles with minutes or kilometres with seconds can make the result look plausible but wrong.
Pace is the inverse of speed
Runners often use pace rather than speed. Pace measures time per unit of distance, such as minutes per mile or minutes per kilometre. A faster pace has a lower time value, which is why pace comparisons can feel different from speed comparisons.
Average speed is not instant speed
A journey's average speed smooths over stops, traffic, hills and changes in effort. It is useful for planning, but it does not show the speed at each moment. Use the formula for broad checks, then add context where real movement is uneven.
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