Pace Predictor
Enter a recent race result to predict your finish times using multiple proven running formulas.
How Race Prediction Works
Our predictions use two proven methods: The Riegel formula (T₁ × (D₂ ÷ D₁)^1.06) accounts for the aerobic and anaerobic demands of different distances. The VDOT method uses Jack Daniels' equivalent performance tables based on your aerobic fitness level. Both assume proper training for the target distance and similar racing conditions.
Race Prediction FAQ
What's the difference between Riegel and VDOT predictions?
We show two proven methods for comparison. The Riegel Formula uses a simple mathematical relationship between distances. VDOT (Daniels method) uses your aerobic fitness level based on established equivalent performance tables. Riegel tends to be more conservative for longer distances, while VDOT accounts for training adaptations.
Which prediction method should I trust more?
Both are scientifically validated. If you're well-trained with good endurance base, VDOT predictions may be more accurate. For newer runners or those without specific distance training, Riegel predictions tend to be more realistic. Use both as a range - your actual performance will likely fall between them.
How accurate are race time predictions?
Race predictions are estimates based on your current performance and established running formulas. Actual results depend on training, race conditions, strategy, and individual physiology. Use predictions as training goals, not guarantees.
What factors affect race performance beyond fitness?
Weather conditions, course elevation, race strategy, nutrition, hydration, sleep, and mental preparation all significantly impact performance. Hot weather and hills typically slow times, while ideal conditions can help you achieve personal bests.
Should I train at my predicted race pace?
Not for all runs. Use predicted paces for specific workouts like tempo runs and race-pace intervals. Most training should be at an easy, conversational pace to build aerobic fitness safely.
Can I use shorter races to predict marathon times?
Yes, but longer predictions become less accurate. A 5K predicts 10K well, but marathon predictions require good endurance base. Marathon performance depends heavily on long run training and fueling strategy.
About the GoPace Running Calculator
GoPace is a free, fast, and mobile-friendly running pace calculator. Whether you’re training for a 5K, 10K, half marathon, or marathon, you can quickly convert between your running pace and expected finish time — or determine the pace required to hit your goal.
Designed with simplicity in mind, GoPace works great on mobile and loads instantly, making it a handy tool for runners of all levels.