Life & Health Β· π Global
Race Pace Predictor
Riegel race time predictor with VDOT training paces and printable wrist-band split card (km/mile).
About this tool
Race Pace Calculator predicts a target-distance finish from a prior race using the Riegel formula T2 = T1 Γ (D2/D1)^1.06, and simultaneously applies the Jack Daniels VDOT table to output four training paces (Easy / Marathon / Threshold / Interval) tuned to your fitness. It auto-generates km/mile splits for the target race in even-split or negative-split strategies and produces a printable wristband card. Accuracy: Β±1β2% for 5Kβ10K, Β±5β10% for 5Kβmarathon under the equal-fitness assumption β among the most-cited running predictions in the world. Runs entirely in the browser.
Use cases
Scenario 1
First marathon target time
Enter a 1:50 half-marathon to get a marathon prediction (~3:55) plus the 4 VDOT training paces.
Scenario 2
Negative-split strategy
A sub-3:30 marathoner prints a negative-split wristband (back 21.1k ~1β2% faster) for race day.
Scenario 3
Four-zone training paces
A VDOT-50 runner gets Easy 5:00/km Β· Marathon 4:25/km Β· Threshold 4:05/km Β· Interval 3:48/km to design the week.
Scenario 4
5K β 10K precise prediction
Predict a 10K finish from your 5K PB at Β±1β2% accuracy and produce the pace board.
Scenario 5
Race-week pace card print
In race week, print the per-km split table, average pace, and target time as a wristband card to use on race day.
Features
- Riegel formula (T2 = T1 Γ (D2/D1)^1.06) prediction
- Jack Daniels VDOT 4-pace zones (E/M/T/I)
- Even and negative split strategies
- km / mile unit toggle
- Printable wristband split card
- 5Kβ10K Β±1β2% / 5Kβfull Β±5β10% accuracy
- Bilingual KO/EN UI
Frequently asked
- Q. How accurate is Riegel?
- A. Β±3β5% under equal fitness; 5Kβ10K is within 1%, 5Kβfull typically 5β10% off. Marathons also depend on training volume, weather, and course.
- Q. What is VDOT?
- A. Jack Danielsβ runner-friendly VO2max proxy (30β85). It maps to predicted times across distances and to the four training-pace zones.
- Q. What separates E/M/T/I paces?
- A. Easy = conversational recovery; Marathon = race pace; Threshold = ~1-hour sustainable tempo; Interval = short bursts to push VO2max.
- Q. Is a negative split better?
- A. Yes β most marathon PRs are negative-split because of glycogen, heat, and mental edge. The tool builds the back ~1β2% faster.
- Q. Any age/sex correction?
- A. Riegel/VDOT are gender-/age-neutral. Masters lose ~0.5β1% per year β apply age-grading separately.
Sources / references
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How we run it / disclaimer
This tool is advisory and does not constitute legal, tax, medical, or financial advice. All calculations and document generation run in your browser; inputs are never sent to a server. Ads follow Google AdSense policy and are kept separate from tool accuracy.