Running Pace Formula: Riegel & VDOT Race Pace Conversion
Pace is time per unit distance. Most coaches think in minutes per kilometer or per mile. Race-equivalent paces across distances follow Daniels' VDOT or Riegel's exponent (~1.06).
Formula
Copy the exact expression or work through it step by step below.
pace_per_km = total_time_seconds / total_distance_km / 60
# Riegel race-equivalence (Pete Riegel, 1977):
T_new = T_known × (D_new / D_known)^1.06 Variables
pace
Pace
Time per unit distance. Minutes-per-kilometer is the metric standard; minutes-per-mile is the US standard.
total_time
Elapsed time
Seconds or minutes. Convert minutes-decimal to minutes:seconds at the end.
total_distance
Distance covered
Kilometers or miles. Be consistent within one calculation.
1.06
Riegel exponent
Empirical constant from Riegel 1977. Models the fact that longer races are slower per km. Works well for 5K–marathon; drift increases beyond marathon distance.
Step By Step
- 1
Express the known race time in seconds.
10K in 45:00 = 2,700 seconds.
- 2
Compute pace per km.
2,700 / 10 = 270 sec/km = 4:30/km.
- 3
For race-equivalent prediction at a new distance, apply Riegel: T_new = T_known × (D_new / D_known)^1.06.
Predicting half marathon from 10K: T_HM = 2,700 × (21.0975 / 10)^1.06 = 2,700 × 2.226 = 6,010 sec ≈ 1:40:10.
- 4
Compute the predicted pace at the new distance.
6,010 / 21.0975 = 285 sec/km = 4:45/km. Half marathon pace is 15 sec/km slower than 10K pace at this fitness.
Worked Example
10K time 45:00, predict half marathon
Known distance
10 km
Known time
45:00
Target distance
21.0975 km (half)
Pace at 10K = 4:30/km. T_HM = 2,700 × (21.0975/10)^1.06 = 6,010 sec → 1:40:10
Predicted half marathon ~1:40:10 at 4:45/km. Real-world performance depends on long-run training and pacing discipline.
Common Variations
Try These Tools
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Race Time Predictor
Race Time predictor: predict finish times across 5K, 10K, half marathon, and marathon from any known race result using Riegel's formula.
Treadmill Pace Converter
Convert treadmill speed to running pace with incline-adjusted flat equivalent, projected race times, and calorie estimates.
FAQ
Questions people ask next
The short answers readers usually want after the first pass.
How do you calculate running pace per kilometer?
What is the Riegel formula for predicting a race time at a new distance?
How do I predict my half marathon time from a 10K?
How does the Riegel formula compare to the Cameron and VDOT models?
Sources & References
- Riegel PS. Athletic records and human endurance — American Scientist (1981)
- Daniels J. Daniels' Running Formula, 4th edition — Human Kinetics