Your Recent Race
Performance Analysis
Predicted Race Times
| Distance | Predicted Time | Pace |
|---|---|---|
| 5K | -- | -- |
| 10K | -- | -- |
| Half Marathon | -- | -- |
| Marathon | -- | -- |
Recommended Training Paces
| Zone | Pace | Purpose |
|---|---|---|
| Easy | -- | Recovery & base building |
| Marathon | -- | Marathon specific endurance |
| Threshold | -- | Lactate threshold improvement |
| Interval | -- | VO2max development |
| Repetition | -- | Speed & running economy |
How Race Prediction Works
Our race time predictor uses the Riegel formula (T₂ = T₁ × (D₂/D₁)^1.06), a widely-validated model that accounts for the non-linear relationship between race distance and performance.
The VDOT score is based on Jack Daniels' methodology, which combines your VO2max with running economy to give a single performance metric. This score determines your optimal training paces across all zones.
For best accuracy, use a recent race result (within the last 4-6 weeks) from a flat course where you gave maximum effort.
Understanding Your Race Predictions
Race prediction models work best when you input a genuine race effort. A training run or time trial typically yields less accurate predictions because environmental and psychological factors differ from actual competition. Use your most recent race result for the best predictions.
The VDOT system also generates training paces specific to your fitness level. Easy pace should feel comfortable enough for conversation. Threshold pace corresponds to the fastest pace you could sustain for about an hour. Interval pace targets VO2max improvement, and repetition pace develops speed and running economy.
Keep in mind that predictions assume equivalent training for the target distance. A runner who has only raced 5K may find their marathon prediction optimistic without the necessary long-run training. Predictions become more accurate as the distance ratio between input and target decreases.
Frequently Asked Questions
How accurate are race time predictions?
For well-trained runners predicting nearby distances (e.g., 5K to 10K), accuracy is typically within 1-2%. Predictions become less reliable when extrapolating to much longer distances or for undertrained runners. The Riegel formula has been validated across thousands of elite and recreational performances.
What is a good VDOT score?
VDOT scores typically range from 20 (beginner) to 85 (world-class). Recreational runners usually score 30-45, competitive club runners 45-55, and elite runners above 60. A 5K time of 25:00 corresponds to roughly VDOT 36, while a 20:00 5K is about VDOT 44.
Does age affect race predictions?
Age grading adjusts your performance relative to the world-record performance for your age and gender. While age does slow absolute performance, age-graded scores allow fair comparison. A 70% age grade is considered competitive at local level, and 80%+ is nationally competitive.
Which race distance should I input?
Input your most recent and best effort race. Shorter race results (5K, 10K) provide good predictions for longer distances when combined with appropriate training. Using a half marathon time to predict a marathon is more accurate than using a 5K time.