Half Marathon Training Plan — 12 Weeks to Race Day
The half marathon is the sweet spot of distance running. Long enough to require real aerobic fitness, short enough to permit threshold-paced racing. Twelve weeks of structured training will get you fitter, faster and ready to race a personal best.
The structure: Base (3 weeks) → Build (5 weeks) → Specific (2 weeks) → Taper (2 weeks). Three quality sessions per week — long run, threshold workout, and either a tempo or a race-pace progression.
Prerequisites
- Running 3–4 days per week, comfortable with a 10–12 km long run
- No active injuries
- Goal time set realistically from a recent 10K or 5K (use VDOT to predict)
- Schedule: 4–7 hours per week at peak
The four phases
Phase 1 — Base (Weeks 1–3)
Goal: aerobic volume and a baseline of intensity through strides.
| Week | Long run | Mid-week quality | Total km/week | Peak Training Load |
|---|---|---|---|---|
| 1 | 13 km easy | Strides 6×100 m | 30–40 | 200–250 |
| 2 | 14 km easy | Hills 6×30 sec | 35–45 | 240–290 |
| 3 (recovery) | 11 km easy | Easy | 25–30 | 150–190 |
Phase 2 — Build (Weeks 4–8)
Goal: introduce threshold and tempo work, extend long runs.
| Week | Long run | Mid-week workout | Total km/week | Peak Training Load |
|---|---|---|---|---|
| 4 | 15 km easy | 3×6 min @ T pace | 40–50 | 290–350 |
| 5 | 16 km easy | 4×6 min @ T pace | 45–55 | 320–390 |
| 6 | 18 km easy | 5×1 km @ T pace | 50–60 | 350–420 |
| 7 (recovery) | 14 km easy | 20 min @ T pace | 35–45 | 200–250 |
| 8 | 19 km easy with last 4 km @ HM pace | 2×3 km @ T pace | 50–60 | 360–430 |
Phase 3 — Half-Marathon-Specific (Weeks 9–10)
Goal: race-pace specificity. Long runs include race-pace blocks; mid-week workouts shift toward race-pace continuous efforts.
| Week | Long run | Mid-week workout | Total km/week | Peak Training Load |
|---|---|---|---|---|
| 9 (peak) | 20 km, 8 km @ HM pace at end | 3×3 km @ T pace | 55–65 | 400–480 |
| 10 | 18 km, 10 km @ HM pace at end | 5 km @ HM pace + 2 km @ T pace | 50–60 | 380–450 |
Phase 4 — Taper (Weeks 11–12)
Goal: shed fatigue while preserving threshold sharpness.
| Week | Long run | Mid-week workout | Total km/week | Peak Training Load |
|---|---|---|---|---|
| 11 | 14 km, last 4 km @ HM pace | 3×1 km @ T pace | 35–45 | 240–290 |
| 12 (race week) | 10 km easy on Tuesday | 4×400 m @ HM pace Wed | 20–30 + race | 120 + 150 |
Pace targets per goal time
| Goal | HM pace | Threshold (T) | Easy (Z2) | Long run (Z2) |
|---|---|---|---|---|
| 2:30 HM | 7:06/km | 6:30/km | 7:30–8:15/km | 7:45–8:30/km |
| 2:15 HM | 6:23/km | 5:50/km | 6:50–7:30/km | 7:00–7:45/km |
| 2:00 HM | 5:41/km | 5:15/km | 6:15–6:50/km | 6:25–7:00/km |
| 1:45 HM | 4:58/km | 4:35/km | 5:30–6:00/km | 5:40–6:10/km |
| 1:30 HM | 4:16/km | 3:55/km | 4:45–5:10/km | 4:55–5:25/km |
| 1:20 HM | 3:48/km | 3:30/km | 4:15–4:40/km | 4:25–4:50/km |
The three variants
First half marathon (just finish)
- Cap long runs at 18 km
- Skip the HM-pace blocks until last 3 weeks — focus on time on feet
- Peak weekly: 40–50 km
Sub-2 half marathon
- Two HM-pace long runs in Phase 3
- One threshold session weekly throughout the build
- Peak weekly: 50–60 km
Sub-1:30 half marathon
- VO₂max sessions every other week alongside threshold work
- Long run with 12 km at HM pace in week 9
- Peak weekly: 70–85 km
The three non-negotiables
- Recovery weeks. Week 3 and week 7 are non-negotiable down weeks. Skip them and your Fitness ramp turns into an injury timeline.
- HM-pace specificity. The half marathon is raced near threshold — your training must include continuous blocks at HM pace, not just intervals.
- 2-week taper. Drop volume 30–40% in week 11, another 30% in week 12. Keep one short threshold session in race week to stay sharp.
Race-day Form target
Aim for Form +10 to +15 on race morning. Fitness should be near peak (no major drops). Half marathon doesn't need the deep taper of marathon — over-tapering loses the threshold sharpness you've built.
Race execution
- First 5 km: 2–5 sec/km slower than target HM pace — let the field thin out
- Km 5–15: exactly target HM pace — this is your race
- Km 15–end: if you're feeling strong, accelerate gently from km 17. The last 2 km should be 5–10 sec/km faster than target
- Fueling: one gel at km 8 and km 14 if pace is sub-1:45; one gel mid-race for slower paces
Common mistakes
- Going out too fast. A 5 sec/km positive split for 5 km early costs 30+ seconds at the line.
- Racing the threshold sessions. T pace = "comfortably hard" — not 10K pace.
- Skipping the long run. The 18–20 km long run with HM-pace finishers is the highest-return session in the plan.
- Aspirational pacing. Set HM pace from current fitness, not goal fitness. Update mid-plan if a tune-up race shows real improvement.
- Untested race-day kit. Shoes, fuel, kit — all tested in long runs first.
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Frequently asked questions about half marathon training
Is 12 weeks enough for a half marathon?
If you have a 10–12 km long run already, yes. Starting from less, add a 4-week base block before week 1.
How long should the longest long run be?
18–22 km for most runners. Going beyond 22 km in half marathon training is unnecessary recovery cost — better to add an HM-pace block instead.
Can I run a 10K race during the plan?
Yes — week 6 or 8 is a good spot. Treat it as a tune-up. Recovery is 3–5 days afterward.
What if I miss the long run one week?
Skip it; don't try to "make it up" mid-week. Resume the next scheduled long run as planned.
Do I need to run faster than HM pace in training?
Yes — threshold pace work (15–25 sec/km faster than HM pace) lifts the ceiling so HM pace feels easier on race day. Without faster work, you'll race at your training intensity.