Marathon Training Pace Calculator
Free marathon training pace calculator turns a recent race time into easy, long-run, marathon, threshold and interval paces, plus a predicted marathon finish time.
Updated 2026-06-14 · Free · No sign-up · Runs privately in your browser
Enter a recent race result to get your training paces and predicted marathon time.
| Training zone | Pace | Purpose |
|---|
Show the formula & steps
How the Marathon Training Pace Calculator Works
This tool converts a recent race result into the full set of training paces you need for a marathon build-up. Enter your race distance and finish time, choose min/km or min/mile, and it returns a predicted marathon time plus easy, long-run, marathon, threshold and interval paces.
The Formula
First it predicts equivalent race times using the well-established Riegel formula:
T2 = T1 × (D2 ÷ D1)^1.06
where T1 is your known time over distance D1, and T2 is the predicted time over distance D2. The exponent 1.06 reflects that pace slows as distance grows.
From those equivalents the calculator derives training zones using standard ratios:
- Easy / recovery ≈ marathon pace × 1.20
- Long run ≈ marathon pace × 1.13
- Marathon pace = predicted marathon time ÷ 42.195 km
- Threshold (tempo) ≈ your 10K-equivalent pace, slightly eased
- Interval (VO2 max) ≈ your 5K-equivalent race pace
Worked Example
A runner with a recent 5K of 22:00 (4:24 /km):
- Predicted marathon ≈ 3:31, marathon pace ≈ 5:00 /km
- Easy pace ≈ 6:00 /km
- Long-run pace ≈ 5:39 /km
- Threshold pace ≈ 4:52 /km
- Interval pace ≈ 4:24 /km
Training Pace Zones at a Glance
| Zone | Relative effort | Used for |
|---|---|---|
| Easy / recovery | ~20% slower than MP | Base mileage, recovery days |
| Long run | ~13% slower than MP | Weekend endurance runs |
| Marathon pace | Goal race pace | Race-pace segments |
| Threshold (tempo) | ~1-hour race effort | Lactate-threshold sessions |
| Interval (VO2 max) | 5K race pace | 3-5 min repeats |
Getting the Most From Your Paces
- Keep easy days easy — most of your weekly volume should sit in the easy zone.
- Re-test periodically: as fitness improves, run a fresh time trial and recalculate.
- Respect conditions: heat, wind and hills all justify easing the target paces on a given day.
Frequently asked questions
How does this marathon pace calculator work?+
Enter a recent race result and the tool uses the Riegel race-time predictor, T2 = T1 × (D2/D1)^1.06, to estimate your equivalent times at other distances. From those it derives your marathon pace and your easy, long-run, threshold and interval training paces.
What pace should I run my easy runs?+
Easy runs should be comfortably conversational, roughly 20% slower than your goal marathon pace. Running easy days truly easy lets you accumulate aerobic volume without excess fatigue, which is what builds endurance over a training block.
What is threshold or tempo pace?+
Threshold (tempo) pace is the effort you could sustain for about an hour of racing, close to your 10K-to-15K race pace. Training at this pace raises your lactate threshold so you can hold faster paces for longer before fatiguing.
How accurate is the predicted marathon time?+
The Riegel formula is a solid statistical estimate that assumes adequate endurance training for the longer distance. It tends to be accurate for well-trained runners but can over-predict the marathon if your weekly mileage and long runs are limited, since the marathon punishes under-trained endurance.
Should I run the marathon at the calculated marathon pace?+
Use it as a target, but adjust for heat, hills, fueling and your training volume. Many runners start slightly slower than goal pace for the first few miles to bank energy, then settle in. The pace assumes even effort on a flat course in good conditions.