Training plans · Marathon
20-week marathon training plan
Twenty weeks gives a marathon build room to breathe. There is a long aerobic base before any hard work, then a steady progression of VDOT-paced quality sessions. This sample is set up for a runner aiming at 3:30 off a 1:38 half marathon.
The plan at a glance
Daniels-style: VDOT-paced quality sessions (E/M/T/I/R) by phase. 30 quality sessions in total, with every fourth week lighter and a taper into race day.
Week by week
| Week | Phase | km | Key sessions | Long run |
|---|---|---|---|---|
| 1 | base | 50 | Threshold run 6 km | 14.4 km |
| 2 | base | 52 | Threshold run 6.2 km | 15.3 km |
| 3 | base | 54 | Threshold run 6.5 km | 16.2 km |
| 4 | base | 45 | Threshold run 5.4 km | 12.3 km |
| 5 | base | 58 | Threshold run 7 km | 18 km |
| 6 | base | 60 | Threshold run 7.2 km | 19 km |
| 7 | build | 62 | Threshold run 7.4 km, Intervals 7.4 km | 19.9 km |
| 8 | build | 52 | Threshold run 6.2 km, Intervals 6.2 km | 15.3 km |
| 9 | build | 66 | Threshold run 7.9 km, Intervals 7.9 km | 21.9 km |
| 10 | build | 69 | Threshold run 8.3 km, Intervals 8.3 km | 23.4 km |
| 11 | build | 71 | Threshold run 8.5 km, Intervals 8.5 km | 24.4 km |
| 12 | build | 58 | Threshold run 7 km, Intervals 7 km | 18 km |
| 13 | peak | 75 | Goal-pace run 9 km, Intervals 9 km | 26.5 km |
| 14 | peak | 77 | Goal-pace run 9.2 km, Intervals 9.2 km | 27.6 km |
| 15 | peak | 79 | Goal-pace run 9.5 km, Intervals 9.5 km | 28.7 km |
| 16 | peak | 65 | Goal-pace run 7.8 km, Intervals 7.8 km | 21.4 km |
| 17 | peak | 83 | Goal-pace run 10 km, Intervals 10 km | 30.9 km |
| 18 | peak | 85 | Goal-pace run 10.2 km, Intervals 10.2 km | 32 km |
| 19 | taper | 64 | Easy running | 20.9 km |
| 20 | taper | 34 | Easy running | Race day |
Training paces
Set from a recent half marathon result, not the goal. Enter your own in the generator and they update.
- Easy5:34/km
- Marathon4:51/km
- Threshold4:32/km
- Interval4:08/km
- Repetition3:58/km
- Goal race4:59/km
What the extra weeks buy you
A longer base. Six weeks of mostly easy running with one threshold session lets mileage rise before the intensity does. That order keeps most runners healthy.
A longer peak, too. Weeks 13 to 18 all carry a goal-pace run and an interval session, with the long run climbing from 26 to 32 km.
Twenty weeks also suits anyone planning around a holiday or a busy month. You can lose a week mid-block and still arrive at the start line on schedule.
Daniels-style paces
Every quality session has a pace derived from your current fitness: easy, marathon, threshold, interval and repetition. The generator calculates them from your recent race, in the spirit of Jack Daniels’ VDOT tables.
For this sample that gives easy runs at about 5:34/km, threshold at 4:32 and intervals at 4:08. Goal pace is 4:59/km.
Why goal pace is slower than marathon pace here
Look at the pace list and you will see marathon pace at 4:51/km, faster than the 4:59 goal pace. That is not a mistake.
Marathon pace is what your 1:38 half predicts you could run today: about 3:24. The goal is set a little slower on purpose, because most amateurs fade more than the prediction allows. The goal-pace runs use 4:59, so they should feel controlled.
If they feel easy by week 15, that is a sign you could aim faster. Test it with a race first.
A checkpoint race around week 10
Race a 10K or half around week 10, when the build phase is under way. Put the new time into the generator, and your remaining sessions shift to match.
Say you run 1:36 for the half. That predicts about 3:20, so your threshold and interval paces sharpen, and a 3:25 goal becomes reasonable. Say you run 1:41 instead. That predicts about 3:30 with no margin, so a 3:35 goal is the safer call. Better to decide that before the peak weeks than on race day.
Frequently asked questions
Is 20 weeks better than 16 for a marathon?
Not better, just gentler. The extra four weeks go into base building. If you are returning from a break or want a slower ramp in mileage, 20 weeks is the safer choice.
What is VDOT?
VDOT is Jack Daniels’ measure of current running fitness, derived from a race result. It maps to a set of training paces. A 1:38 half marathoner trains at different paces from a 1:50 one.
Does the plan change if I enter a different goal?
Your goal sets the goal-pace sessions; your recent race sets everything else. If the goal is much faster than your recent race predicts, the generator warns you.