Race Time Comparison Tool
Compare two race performances against the same mathematical model.
Stronger Performance:
Roughly equivalentAnalysis:
Your 10K was 0.2% faster than the Riegel prediction from your 5K.
Based on your 5K: Your 10K model estimate is 52:07 (actual: 52:00)
Based on your 10K: Your 5K model estimate is 24:56 (actual: 25:00)
Use the percentage difference to compare your performances across distances. Consider the course, weather, race dates, and your preparation when reviewing what contributed to each result.
See the comparison formulaRace-time reference
| 5K result | 10K | Half marathon | Marathon |
|---|---|---|---|
| 20:00 | 41:42 | 1:32:00 | 3:11:49 |
| 25:00 | 52:07 | 1:55:00 | 3:59:47 |
| 30:00 | 1:02:33 | 2:18:00 | 4:47:44 |
How we calculate this
Target time = known time × (target distance ÷ known distance)^1.06.
The predictor and comparison tool use the same equation. The comparison reports how much faster or slower your second result is than the prediction from your first result. Differences within 1% are labeled roughly equivalent; that cutoff is a RaceThere display convention.
Sources: Vickers & Vertosick (2016): race prediction in recreational runners.
Using your results
Start with a recent race that reflects your current fitness. Predictions are most useful between similar distances; for marathons and ultras, weigh the result alongside your long runs, fueling practice, and course conditions. When comparing two results, consider how your preparation and race-day conditions differed.
Common questions
How can I use a 5K result to set a marathon goal?
Use the predicted time as a starting point, then compare it with your long-run pace, recent longer races, and marathon preparation. Fueling, weather, and the course also shape your race-day goal.
How is the comparison percentage calculated?
We subtract the predicted second-race time from the actual second-race time, divide by the prediction, and multiply by 100. A positive result means the actual second race was slower than the model prediction.