Half marathon training plan: 12-week program

The half marathon (21.097 km / 13.1 miles) is the perfect distance: long enough to be a real challenge, short enough not to destroy your body. Whether you're targeting your first finish or a sub-2-hour time, here's a complete 12-week plan.

Prerequisites

This plan assumes you can already run 30-40 minutes non-stop and have been running at least 2-3 times per week for a few months. If not, start with a base-building plan for 6-8 weeks first.

Plan structure

The plan is organized in 3 phases:

Phase 1: Base building (weeks 1-4)

Building your aerobic foundation. 3-4 runs per week including a progressive long run (10 km → 14 km). Volume goes from 25 to 35 km/week. All runs are at easy pace (you can hold a conversation).

Phase 2: Development (weeks 5-9)

Adding quality workouts. Volume builds to 40-50 km/week. Key sessions:

Long run: 15 km → 18 km, with the last 5 km at half marathon pace
Intervals: 6-8 × 1000 m at 10K pace (90s jog recovery)
Tempo: 2-3 × 3 km at half marathon pace (2 min jog recovery)
Easy runs: 2 runs at easy pace (45-60 min)

Phase 3: Taper (weeks 10-12)

Reduce volume by 30-40% while maintaining intensity. Last long run (15 km) in week 10. Week 12: 3 short easy runs, rest the day before.

Finding your target pace

Half marathon pace is between 85-90% of your VO2max pace, or roughly 15-20 seconds slower than your 10K pace.

Examples:

Target 2:00 → pace 5'41/km → calculate your splits
Target 1:45 → pace 4'58/km
Target 1:30 → pace 4'16/km

Race day nutrition

3h before: carb-rich breakfast (white bread, jam, banana). Avoid fiber and fat.

During: one gel at 45 min, a second at 1h15. Drink at aid stations (small sips). For sub-1:45, water alone is enough. Beyond that, add carbs.

After: recovery drink within 30 min, full meal within 2h.

The 5 half marathon mistakes

1. Going out too fast

Trap number one. Starting adrenaline masks the real effort. Result: hitting the wall at 15 km. Strategy: run the first 3 km 10 seconds slower than target pace.

2. Testing gear on race day

New shoes = guaranteed blisters. All your equipment should be tested in training.

3. Neglecting recovery

Overtraining is the invisible enemy. One full rest day per week is non-negotiable.

4. Skipping warm-up

10 minutes easy jog + a few progressive strides before the start activates your cardiovascular system and reduces injury risk.

5. Ignoring the weather

In hot weather (> 25°C / 77°F), slow down by 10-15 seconds per km. Hydration becomes critical.

Ready to start?

RaceDayLab offers free half marathon plans, from beginner to expert, with all workouts detailed week by week.

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To calculate your training paces and splits, use our free pace calculator.