12 Week Marathon Training Plan
Twelve weeks is a short marathon build, so it only works if the base is already there. This plan is for runners who have finished a half marathon or a solid block of training and want to turn that fitness into a marathon. Four runs a week, a long run from 18 km to 32 km (11 to 20 miles), two easier weeks and a three-week step-down to race day.
Who it is for: you run about 40 km (25 miles) a week, four times a week, and your long run is already 16–18 km (10–11 miles). If that is a stretch, take the 14 week half marathon to marathon plan instead, or the 16 week beginner plan if this is your first long race.
Health note. General plan, not medical advice. If you have a heart condition, chest pain, dizziness, an injury, are pregnant or are coming back after a long break, check with a doctor first. Stop and seek help if you feel unwell.
The plan, week by week
Distances are for the whole week. The long run and the key session are part of that total; the rest is easy running over the other two runs.
| Week | Phase | Long run | Key session | Week total |
|---|---|---|---|---|
| 1 | Build | 18 km | 3 × 8 min threshold, 2 min jog | 42 km |
| 2 | Build | 20 km | 10 km steady with 5 km at marathon pace | 46 km |
| 3 | Build | 22 km | 4 × 8 min threshold, 2 min jog | 50 km |
| 4 | Easier week | 16 km | Easy runs only, 6 × 20 s strides | 38 km |
| 5 | Build | 24 km | 14 km with 8 km at marathon pace | 54 km |
| 6 | Peak | 27 km | 3 × 10 min threshold, 2 min jog | 58 km |
| 7 | Peak | 29 km | 16 km with 10 km at marathon pace | 61 km |
| 8 | Easier week | 21 km | Easy runs, or a half marathon tune-up race as the long run | 45 km |
| 9 | Peak | 32 km | 18 km with 12 km at marathon pace | 64 km |
| 10 | Taper | 24 km | 12 km with 8 km at marathon pace | 50 km |
| 11 | Taper | 16 km | 10 km with 5 km at marathon pace | 36 km |
| 12 | Race week | — | 3 short easy runs, 2 with 4 × 20 s strides + RACE | 17 km |
Each key session starts with 10–15 minutes easy and ends with 10 minutes easy. Strides are 20 seconds of quick, relaxed running with a walk back. Threshold is "comfortably hard": a few words, not sentences.
Your paces
Pick your goal time in the marathon pace calculator or read the pace table. Three examples (Daniels and Gilbert equations):
| Goal | Easy /km (/mile) | Threshold /km (/mile) | Marathon pace /km (/mile) |
|---|---|---|---|
| 3:30:00 | 5:22–6:25 (8:38–10:20) | 4:40–4:54 (7:31–7:53) | 4:59 (8:01) |
| 4:00:00 | 6:06–7:17 (9:49–11:44) | 5:19–5:34 (8:33–8:58) | 5:41 (9:09) |
| 4:30:00 | 6:51–8:09 (11:01–13:07) | 5:58–6:15 (9:36–10:04) | 6:24 (10:18) |
Base the goal on a recent race, not on hope. A half marathon in 1:50:00 predicts about 3:49:21 with the Riegel formula, and that assumes the long runs get done. The marathon time predictor works it out for you.
Why 12 weeks is tighter than 16
With four fewer weeks, the plan has only two easier weeks (4 and 8) and the long run grows by about 2–3 km a week. There is little room to make up lost time. That is why the start level matters: the first week already has an 18 km long run.
The step-down starts after the 32 km week. Week 10 has about 20 % less running than the peak and week 11 about 45 % less, while the marathon-pace blocks stay. That follows the taper meta-analysis by Bosquet et al. (2007): about two weeks, volume down 41–60 %, intensity kept.
When the plan should bend
A short plan tempts you to push through. Don't. Before each key session and long run, use the green/amber/red daily check for sleep, morning resting heart rate, legs and stress. An amber day becomes easy; a red day becomes rest. If you lose more than a week to illness or injury, a 12 week plan rarely recovers, so consider a later race.
Flemming, the coach behind this site, plans the same way: he reviews every session his athletes log and moves or drops hard days when stress, sleep or training say so. See personal coaching if you want that support.
Print the plan
Choose km or miles and press PDF (A4) or PDF (US Letter) for the week table, the daily check and the health note on one page.
Questions and answers
Can I train for a marathon in 12 weeks?
Yes, if you already run about 40 km (25 miles) a week and your long run is 16–18 km. Starting from less, 12 weeks is short, and the 14 week half marathon to marathon plan is safer.
What is the longest run in the 12 week plan?
32 km (20 miles) in week 9, three weeks before race day.
Can I run a half marathon during the plan?
Yes. Week 8 is built for it: run a half marathon tune-up as that week's long run, then use the result to check your marathon goal.
Is a 12 week plan good after a half marathon?
Yes, if you already run about 40 km a week. Take an easy week after the half, then start week 1. If your weekly distance is closer to 30 km, the half marathon to marathon plan gives you two more weeks.
What if I am short on time and only have 10 weeks?
Start at week 3, but only if your long run is already about 22 km. Otherwise choose a later race.
Sources
- Bosquet, L., Montpetit, J., Arvisais, D. & Mujika, I. (2007). Effects of tapering on performance: a meta-analysis. Medicine & Science in Sports & Exercise, 39(8), 1358–1365.
- Riegel, P. S. (1981). Athletic records and human endurance. American Scientist, 69(3), 285–290. (Table 1: men 1.07732, women 1.08283; men over 40 to over 70: 1.05352–1.06370.)
- Daniels, J. & Gilbert, J. (1979). Oxygen Power: Performance Tables for Distance Runners. Tempe, AZ: Daniels and Gilbert. Daniels, J. Daniels' Running Formula. Human Kinetics.
- The plan itself is our own and follows common principles: mostly easy running, one long run a week, easier weeks and a taper.