Fitness Forecast
Most calculators tell you what you can run today. This one projects forward: given a recent race and how you'll train, here's what you could be capable of on race day.
Projected fitness change: VDOT 40 → 41.2 (+1.2 over 12 weeks at 4 days/week)
| Distance | Today | Realistic | Stretch |
|---|---|---|---|
| 5K | 23:56 | 23:21 | 23:07 |
| 10K | 49:55 | 48:42 | 48:11 |
| Half Marathon | 1:50:09 | 1:47:27 | 1:46:20 |
| Marathon | 3:49:41 | 3:44:03 | 3:41:43 |
Projections are typical ranges from training research, not a guarantee — individual response, consistency, and health all vary.
How the forecast works
We turn your recent race into a VDOT fitness score (Daniels’ model), then estimate how much it improves over your training block. The gains are deliberately conservative because that’s what the research shows:
- Trained runners typically gain only 1–2 VDOT points per cycle; beginners more (~2–4), advanced runners less (under ~1).
- Gains are front-loaded — most arrive in the first 4–8 weeks, then plateau, so a 20-week block isn’t twice a 10-week one.
- The fitter you already are, the smaller each additional gain.
- More days per week means more stimulus — up to a point.
A forecast tells you what’s within reach; a structured plan is how you get there. The “stretch” column is an optimistic-but-possible target if everything clicks.
Ready to train toward it?
Build a free, personalized plan that uses these paces and progresses you safely to race day.
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