Tools Race Time Predictor
What could you run?
Enter one recent race result and this tool predicts your times at 5K, 10K, half marathon and marathon using the Riegel formula, with the exponent tuned to your weekly volume — because a 70km-a-week runner holds pace over distance far better than a 25km-a-week runner with the same 5K.
Predicted marathon
3:43:07
| DISTANCE | PREDICTED | PACE (/KM) |
|---|---|---|
| 5K | 23:16 | 4:39 |
| 10K (your race) | 48:30 | 4:51 |
| Half marathon | 1:47:01 | 5:04 |
| Marathon | 3:43:07 | 5:17 |
Asked often
- How does the race time predictor work?
- It uses the Riegel formula — T2 = T1 × (D2/D1)^k — which models how pace decays as race distance grows. The classic exponent is 1.06; this tool adjusts it for weekly volume, because higher-mileage runners hold pace better over longer distances.
- How accurate are race time predictions?
- Good for one step up in distance from a recent, honest race effort. A 10K predicts a half well; predicting a marathon from a 5K stretches the model, and endurance-specific training still has to be done. Treat predictions as targets to train toward, not promises.
- Why does weekly mileage change my prediction?
- Two runners with the same 5K time rarely run the same marathon. The one running 70km weeks has the aerobic base to hold pace late; the one on 25km weeks usually fades. The exponent shift reflects that reality.
A prediction is a gap. RunV closes it.
The predictor shows what your fitness is worth today — RunV builds the adaptive plan that turns it into a finish line, then see what your goal takes.
