Marathon Training Plan — 16 Weeks Preparation
16 weeks is the sweet spot for marathon training: long enough to build fitness from a reasonable base, short enough to stay focused. This plan walks through the four phases, the three key sessions per week, and the 3-week taper that gets you to the start line strong.
The structure: Base (4 weeks) → Build (5 weeks) → Specific (5 weeks) → Taper (2–3 weeks). Three quality sessions per week — long run, midweek workout, weekend tempo or marathon-pace run — with easy runs filling the rest.
Prerequisites
- Currently running 4+ days per week, comfortable with a 9–10 mi (14–16 km) long run
- No injuries — marathon training amplifies any existing weakness
- Realistic goal time based on a recent half marathon or 10K (use VDOT to predict)
- Schedule willing to absorb 6–10 hours per week at peak
The four phases
Phase 1 — Base (Weeks 1–4)
Goal: build aerobic volume. Mostly Zone 2 running with strides and occasional hills.
| Week | Long run | Mid-week quality | Weekly miles (km) | Peak Training Load |
|---|---|---|---|---|
| 1 | 10 mi (16 km) easy | Strides 6×100 m | 25–31 (40–50) | 250–300 |
| 2 | 11 mi (18 km) easy | Hills 6×30 sec | 28–34 (45–55) | 280–340 |
| 3 | 12 mi (20 km) easy | Strides 8×100 m | 31–37 (50–60) | 320–380 |
| 4 (recovery) | 9 mi (14 km) easy | Easy | 19–25 (30–40) | 180–230 |
Phase 2 — Build (Weeks 5–9)
Goal: introduce threshold work and longer long runs. Quality sessions become the centerpiece.
| Week | Long run | Mid-week workout | Weekly miles (km) | Peak Training Load |
|---|---|---|---|---|
| 5 | 14 mi (22 km) easy | 3×8 min @ T pace | 34–40 (55–65) | 380–450 |
| 6 | 15 mi (24 km) easy | 4×8 min @ T pace | 37–43 (60–70) | 420–490 |
| 7 | 16 mi (26 km) easy | 5×1 km @ T pace | 40–47 (65–75) | 460–530 |
| 8 (recovery) | 11 mi (18 km) easy | 20 min @ T pace | 25–31 (40–50) | 240–290 |
| 9 | 17 mi (28 km) with last 3 mi (5 km) @ M pace | 6×1 km @ T pace | 40–47 (65–75) | 490–560 |
Phase 3 — Marathon-Specific (Weeks 10–14)
Goal: simulate race-day demands. Long runs include marathon-pace blocks; midweek workouts shift toward race-specific intervals.
| Week | Long run | Mid-week workout | Weekly miles (km) | Peak Training Load |
|---|---|---|---|---|
| 10 | 19 mi (30 km), 5 mi (8 km) @ M pace at end | 2×3 km @ T pace | 43–50 (70–80) | 540–620 |
| 11 | 20 mi (32 km), 6 mi (10 km) @ M pace at end | 3×3 km @ T pace | 47–53 (75–85) | 580–680 |
| 12 (recovery) | 14 mi (22 km) easy | 20 min @ T pace | 31–37 (50–60) | 290–350 |
| 13 | 21 mi (34 km), 7 mi (12 km) @ M pace at end | 2×5 km @ HM pace | 47–56 (75–90) | 600–700 |
| 14 (peak) | 20 mi (32 km) with 10 mi (16 km) @ M pace | 3×4 km @ T pace | 50–59 (80–95) | 640–740 |
Phase 4 — Taper (Weeks 15–16)
Goal: reduce fatigue while preserving fitness. Volume drops; intensity stays.
| Week | Long run | Mid-week workout | Weekly miles (km) | Peak Training Load |
|---|---|---|---|---|
| 15 | 14 mi (22 km), last 5 mi (8 km) @ M pace | 3×1 km @ T pace | 34–40 (55–65) | 340–410 |
| 16 (race week) | 7 mi (12 km) easy on Tuesday | 2×1 km @ M pace Wed | 19–25 (30–40) + race | 180 + 280 |
Pace targets per goal time
| Goal | Marathon (M) | Threshold (T) | Easy (Z2) | Long run (Z2) |
|---|---|---|---|---|
| 5:00 marathon | 11:27/mi (7:07/km) | 10:28/mi (6:30/km) | 12:04–13:17/mi (7:30–8:15/km) | 12:28–13:41/mi (7:45–8:30/km) |
| 4:30 marathon | 10:18/mi (6:24/km) | 9:23/mi (5:50/km) | 11:00–12:04/mi (6:50–7:30/km) | 11:16–12:28/mi (7:00–7:45/km) |
| 4:00 marathon | 9:09/mi (5:41/km) | 8:27/mi (5:15/km) | 10:04–11:00/mi (6:15–6:50/km) | 10:20–11:16/mi (6:25–7:00/km) |
| 3:30 marathon | 8:01/mi (4:59/km) | 7:23/mi (4:35/km) | 8:51–9:39/mi (5:30–6:00/km) | 9:07–9:55/mi (5:40–6:10/km) |
| 3:00 marathon | 6:52/mi (4:16/km) | 6:18/mi (3:55/km) | 7:39–8:19/mi (4:45–5:10/km) | 7:55–8:43/mi (4:55–5:25/km) |
| 2:45 marathon | 6:18/mi (3:55/km) | 5:46/mi (3:35/km) | 7:06–7:47/mi (4:25–4:50/km) | 7:15–7:55/mi (4:30–4:55/km) |
The three variants
First marathon (just finish)
- Cap long runs at 19 mi (30 km) — beyond that, recovery cost outweighs the benefit for first-time finishers
- Skip M-pace blocks until the last 4 weeks — focus on time on feet
- Target peak weekly: 37–43 mi (60–70 km)
Sub-4 marathon
- Two M-pace long runs per cycle, 9–11 mi (14–18 km) at M pace
- Threshold sessions weekly during build phase
- Peak weekly: 43–53 mi (70–85 km)
Sub-3 marathon
- Three M-pace long runs per cycle, including a 19 mi (30 km) with 12 mi (20 km) at M pace
- Threshold + VO₂max blocks; peak week with 5×1 mile at threshold
- Peak weekly: 56–68 mi (90–110 km)
The three non-negotiables
- Recovery weeks every 4 weeks. Drop volume by 40%. Skip these and you'll arrive at the start line stale or injured.
- One marathon-pace long run every 2–3 weeks in Phase 3. Race-day specificity matters — your legs need to know what 19+ mi (30+ km) at M pace feels like.
- Honest tapering. Reduce volume 40% in week 15, another 30% in week 16. Resist the temptation to do "one more" hard session — fitness is already banked.
Race-day Form target
Aim for Form +15 to +25 on race morning. Fitness should still be 75–95 (depending on your peak). Lower Form means you're under-tapered; much higher means Fitness has dropped too far.
Common mistakes
- Skipping the long M-pace runs. They're the highest-return single session in the plan.
- Racing the threshold sessions. T pace is by feel "comfortably hard" — not 5K pace. Stay in zone.
- Big mileage jumps. No more than 10% volume increase per week in build phases. Fitness ramp > 5/week is risky.
- New shoes on race day. Break in race shoes for 62+ mi (100+ km) in long runs first.
- Ignoring sleep. Fitness of 80 with 6 hours of sleep is worse than Fitness of 65 with 8 hours.
Frequently asked questions about marathon training
Is 16 weeks enough for a first marathon?
If you're already running 4+ days/week with a 9 mi (14 km) long run, yes. If you're starting from less, plan a 4-week base block before week 1 — that's a 20-week build in total.
How long should the longest long run be?
For most runners, 20–22 mi (32–35 km). Going longer than 22 mi (35 km) adds little fitness and a lot of recovery debt. The exception: sub-3 runners doing M-pace simulations may run 20 mi (32 km) with 12+ mi (20+ km) at M pace.
Can I race a half marathon during the plan?
Yes — week 11 or 13 is a great spot. Treat it as a tune-up, not a goal race; recover for 5–7 days afterward.
What if I miss a week from illness?
Drop the missed week from the plan; don't try to make it up. Resume at the volume you were at before, or 80% of it if illness was severe. Adaptive AI plans (like WattRun's) auto-recompute around missed weeks.
Do I need to do a 20 mi (32 km) long run?
Not necessarily. Many sub-3:30 runners cap their long run at 17–19 mi (28–30 km) but with significant M-pace blocks (7–10 mi (12–16 km) at marathon pace). Time on feet matters; absolute distance is secondary.