Half Marathon Training Plan: 12-Week Guide

A half marathon training plan is the structured roadmap that takes you from your current fitness level to crossing the 21.1 km (13.1 mile) finish line feeling strong. Whether you have never raced before or want to beat your personal best, following a properly periodised 12-week plan is the single biggest predictor of race-day success — more important than any pair of shoes or energy gel strategy.

This guide gives you a complete week-by-week training schedule, explains how to fuel and recover between sessions, and answers the questions most runners ask before their first or second half marathon. If you also do strength and conditioning work alongside your running, our guide on full body workout plans shows how to layer lifting sessions without compromising run quality.

Who Is This Half Marathon Training Plan For?

This 12-week plan is designed for runners who can already complete a 5 km run without stopping. It suits:

• First-timers who want a conservative, injury-aware build-up to the finish line
• Recreational runners targeting a time between 1:45 and 2:30
• Cross-training athletes — including obstacle and functional fitness competitors preparing for events like HYROX — who need a dedicated running block
• Returning runners rebuilding after injury or a long break

Runners already capable of 30–35 km per week and targeting sub-1:45 should add an extra easy run and increase long-run distances by 10–15%.

The 12-Week Half Marathon Training Plan

Each week contains four run types: long run (aerobic base), intervals (speed and lactate threshold), easy run (active recovery and aerobic volume), and rest or cross-training. Weekly mileage increases by roughly 10% per week, with a deload every fourth week.

Pace guide: Easy = conversational pace, you can speak in full sentences. Tempo = comfortably hard, can manage a few words. Interval = 5 km race effort or harder.

How to Progress Through the Plan

The 10% rule governs this schedule: never increase total weekly mileage by more than 10% from one week to the next, except during planned deload weeks. Here is how each phase works:

• Weeks 1–4 (Base building): Establish the habit of four-day running weeks. Keep all runs fully aerobic. The interval sessions build neuromuscular efficiency without generating significant fatigue.
• Weeks 5–8 (Threshold development): Longer tempo efforts train your body to sustain race pace. The deload in week 8 consolidates fitness gains before the peak block.
• Weeks 9–10 (Peak): Highest mileage of the plan. The 19 km long run builds the aerobic confidence needed to hold form in the second half of the race.
• Weeks 11–12 (Taper): Volume drops sharply but intensity is maintained. This is where fitness solidifies. Trust the process — feeling sluggish in taper week is normal.

If you want the underlying principles behind periodisation and progressive overload for any training goal, our article on how to create a workout plan explains frequency, volume, and intensity frameworks in detail.

Nutrition for Half Marathon Training

Running performance is inseparable from nutrition. These principles apply across the full 12 weeks:

• Daily carbohydrate intake: Aim for 5–7 g of carbohydrate per kg of bodyweight on moderate training days, rising to 7–10 g/kg on long-run days. Carbohydrates fuel both aerobic and threshold work.
• Protein for recovery: Consume 1.6–2.0 g of protein per kg of bodyweight daily. Running creates micro-damage in muscle tissue; adequate protein accelerates repair and reduces injury risk.
• Pre-run fuelling: For runs longer than 75 minutes, eat a carbohydrate-rich meal 2–3 hours before, or a smaller snack (banana, toast with jam) 30–45 minutes before.
• In-run fuelling: On long runs of 13 km or more, take 30–60 g of carbohydrates per hour via gels, chews, or sports drink. Practice this in training — do not try new products on race day.
• Post-run recovery window: Consume a 3:1 or 4:1 ratio of carbohydrates to protein within 30–45 minutes after long runs and hard interval sessions. Chocolate milk, a banana with Greek yoghurt, or a recovery shake all work well.
• Hydration: Drink to thirst during normal runs. On long runs in warm conditions, aim for 400–800 ml per hour and consider electrolyte supplements if you sweat heavily.

Recovery Strategies

Adaptation happens during recovery, not during the run itself. These strategies protect training consistency:

• Sleep: Seven to nine hours per night is the single most powerful recovery tool available. Growth hormone secretion and glycogen replenishment peak during deep sleep.
• Easy-day discipline: Easy runs should feel almost embarrassingly slow — many runners make their easy days too hard and their hard days insufficiently hard. Use a heart rate monitor and stay below 75% of maximum heart rate on recovery days.
• Foam rolling and mobility: 10 minutes of post-run rolling on calves, IT band, hip flexors, and glutes reduces delayed-onset muscle soreness and maintains range of motion.
• Strength training: One or two sessions of lower-body strength work per week (single-leg squats, hip thrusts, calf raises) reduces injury risk by strengthening the tendons and stabilisers that running alone does not address. Keep these sessions light in peak weeks.
• Listen to your body: If resting heart rate is elevated by more than 5–7 bpm, replace an interval session with an easy run or rest day. Overtraining is the most common reason amateur runners miss their goal race.

Common Mistakes in Half Marathon Preparation

• Skipping the long run: The weekly long run is the cornerstone of half marathon fitness. Every other session exists to support it. Missing two or more in a 12-week block significantly undermines race-day preparedness.
• Racing easy runs: Running at a comfortable conversational pace feels unproductive, but it builds the aerobic base that makes threshold work possible. Runners who push easy days accumulate fatigue and plateau.
• Ignoring strength and conditioning: Runners who skip strength work are significantly more likely to suffer a lower-extremity injury. Even two 20-minute sessions per week of single-leg and hip work make a meaningful difference.
• Trying new gear on race day: Shoes, socks, gels, and clothing should all be tested extensively in training. Blisters, chafing, or gastrointestinal distress caused by unfamiliar products can derail months of preparation in the first five kilometres.
• Going out too fast: Most recreational runners run the first 5 km of a half marathon 15–20 seconds per kilometre faster than their target pace, then pay dearly in kilometres 15–21. Practise race pace in weeks 9 and 10 so it feels automatic.

Frequently Asked Questions

How long does it take to train for a half marathon?

Twelve weeks is the standard minimum for runners who can already run 5 km comfortably. Complete beginners — those who currently run fewer than 15 km per week — benefit from an extended 16–20 week plan that incorporates a run/walk base-building phase before the structured schedule above begins.

How many days per week should I run?

Four days per week is the optimal balance for most amateur half marathon runners. It provides enough volume to build aerobic capacity and race-specific fitness while leaving adequate recovery time. Running five or six days per week is appropriate only for runners already accustomed to high mileage who are targeting sub-1:45.

What is the ideal long-run pace?

Long runs should be completed at 60–75 seconds per kilometre slower than your goal half marathon pace. This pace keeps you in Zone 2 heart rate (65–75% of maximum), maximises fat oxidation, builds mitochondrial density, and avoids excessive muscle damage. If you finish a long run feeling fresh, you ran it correctly.

Should I do strength training alongside this plan?

Yes — one to two lower-body strength sessions per week reduce injury risk and improve running economy. Prioritise single-leg exercises (Bulgarian split squats, single-leg Romanian deadlifts, calf raises) that mimic the unilateral demands of running. Schedule strength sessions on the same day as interval or tempo runs — never on rest days — to protect recovery time.

What should I eat the night before a half marathon?

Eat a familiar, carbohydrate-rich dinner that you have had before long training runs: pasta, rice, or potatoes with a moderate protein source and minimal fibre and fat. Avoid experimenting with new foods. Aim to eat 3–4 hours before race-day start if possible, or a light carbohydrate snack 60–90 minutes before. Hydrate steadily throughout the day before the race rather than drinking large volumes immediately before the gun.

Personal trainers can build and deliver this plan to clients — including custom progressions, GPS-synced run data, and automated check-ins — with Trainero software.