Turn a recent race result into realistic finish-time estimates — and the training paces to hit them.
Based on your recent race performance, predict your finish times for other distances using proven formulas.
Note: These predictions assume consistent training and similar race conditions. Factors like weather, elevation, and fitness can significantly affect actual performance.
Enter your most recent race distance and finish time. The predictor estimates your equivalent times at the 5K, 10K, half marathon, and marathon, and suggests the training paces that match your current fitness. For the best result, use a race you ran hard and recently — fitness changes quickly.
A prediction is a starting point, not a finish line. If the predictor says you can run a 1:55 half but you have not done the specific long runs and tempo work, treat the number as a target to train toward, not a pace to attempt cold. Plug the predicted pace into the pace calculator to plan your splits, then follow a structured training plan to close the gap.
Predictions are most accurate when based on a recent, all-out race at a similar-ish distance, and when you have trained specifically for the target distance. A 10K result predicts a half marathon well; a 5K result is less reliable for the marathon because endurance, fueling, and pacing play a bigger role the longer you go. Treat the prediction as a realistic ceiling, not a guarantee.
VDOT is a single number, popularized by coach Jack Daniels, that represents your current running fitness based on a race performance. Once your VDOT is known, equivalent times at other distances and your ideal training paces (easy, tempo, interval) can be derived from it. This predictor uses the same proven equivalency model.
Because fatigue compounds over distance. A common rule of thumb is that your marathon is roughly your half marathon time doubled plus 10–20 minutes, assuming proper marathon-specific endurance training. Runners who skip long runs tend to slow even more in the final 10K.
Run the bulk of your weekly mileage at the easy pace, use tempo pace for sustained threshold efforts, and reserve interval pace for short, hard repeats. Training at the right paces — not just running hard every day — is what actually moves your race prediction faster over a training block.