Will You Break 2 Hours?
Enter your recent 5K or 10K time and we'll predict your half marathon finish time, show you where you rank in your age group, and give you the exact paces to train at.
Free. Instant. No signup.
Check Your Half Marathon Readiness
How This Works
We use the same Jack Daniels VDOT formula that elite coaches use to predict your running performance. Enter your most recent race time (5K, 10K, or half marathon), and we calculate:
- •Your aerobic capacity score — A VO2 max equivalent that determines your exact training paces
- •Predicted half marathon time — What you'll run in 12 weeks if you train smart
- •Your age-group percentile — Where you rank vs. runners your age (top 30%? top 50%?)
- •Training pace zones — Exactly what pace to run your easy runs, threshold runs, and speed work
Why This Matters
Most runners run their easy runs too fast and their hard runs too easy. Your training paces are calculated from your actual fitness, not a generic template. This prevents injury and makes you faster.
What's Your Next Step?
Once you see your prediction and your paces, you can build a full 12–20 week personalized training plan for €9.99 one-time. No subscription. Your plan is yours forever. Download it as a PDF, email it to yourself, share it with your coach.
💡 Pro Tip:
Your easy pace probably feels slower than you think it should. That's correct. Easy runs should feel easy — they build aerobic base. Your threshold and interval runs are where you build speed.
Questions?
Is this prediction accurate?
The Jack Daniels formula is used by Olympic coaches. It's accurate ±5% for most runners. Your actual half marathon time depends on training consistency, race conditions, and how well you execute pacing on race day.
What if my race was really hard (or really easy)?
Use your best representative recent race. If your last race was a "bad day" with stomach issues or bad conditions, use the one before that. The formula works best with races run in optimal conditions.
Can I use a training run's pace instead of a race?
Ideally no — race pace is more reliable because it's an all-out effort. But a recent 10K time trial works if you don't have a recent race.
Why do you ask for age?
To show you your age-group percentile ranking. A 2:00 half marathon for a 45-year-old is genuinely impressive (top 30%), while for a 30-year-old it's intermediate. Age-group context matters.
What do the pace zones mean?
Easy: Should feel conversational. Build aerobic base.
Threshold: Comfortably hard. Builds lactate threshold.
Interval: Hard breathing. Builds VO2 max.
Each serves a purpose in your training plan.
What if I'm a beginner?
This predictor works for all levels. If you don't have a recent race time, use your average pace from your longest training run. The formula will still be directionally accurate.
Ready to Train Smart?
Get your personalized 12–20 week training plan built from your fitness level. Every session explained.
Build Your Plan → €9.99