Running pace is time divided by distance. Once the units are consistent, pace, speed, and projected finish time can be converted cleanly.
Pace and speed are opposites
A pace of 8 minutes per mile means each mile takes eight minutes. Speed expresses distance per unit of time, so a faster run has a lower minutes-per-mile number but a higher distance-per-hour number.
Keep the units consistent
A mile is longer than a kilometer, so the numerical pace changes when the distance unit changes. Convert the distance before dividing time, and keep hours and minutes in a consistent format.
Treat projections as estimates
A short test pace may not hold over a longer distance. Weather, hills, fueling, fatigue, and training all affect performance. Use a projection to plan, not to guarantee a race result.
A worked example
Worked example: 24 minutes over 3 miles is 8 minutes per mile. The same performance expressed over 4.828 kilometers has a different numerical pace, but it describes the same run.
For a finish projection, use a distance and recent performance that resemble the event. Hills, weather, fueling, and fatigue can make a straight-line projection optimistic.
Race conditions can add meaningful time even when the distance is unchanged. Compare a projection with recent runs on similar terrain and leave room for a controlled start rather than planning at the fastest possible pace.
Once pace is defined clearly, the arithmetic is simple; the uncertainty comes from whether the performance can be sustained.
COMMON QUESTIONS
Frequently asked questions
Is a lower pace number faster?
For minutes per mile or kilometer, yes. Fewer minutes per distance unit means faster running.
Why is my race projection optimistic?
Short-distance speed, fatigue, terrain, and conditions may not translate directly to a longer event.