How to Train for a Marathon

A comprehensive 16-week plan to take you from half marathon fitness to crossing the marathon finish line at 26.2 miles.

Key Takeaways

  1. You should be running 25+ miles per week with a recent half marathon or equivalent long run before starting this plan.
  2. Your longest training run peaks at 20 miles — you do NOT need to run 26.2 miles before race day.
  3. The marathon is primarily an endurance and fueling challenge. Running the right pace and eating enough during the race matters more than fitness alone.
  4. "The Wall" at mile 18–22 is caused by glycogen depletion. Proper fueling during the race prevents or reduces it.

Prerequisites

This plan assumes you've completed at least one half marathon (or have been running 25+ miles per week for 3+ months) and can comfortably run 10+ miles. If you haven't raced a half marathon yet, complete the half marathon plan first — it's a critical stepping stone.

You'll need:

The 16-Week Marathon Training Plan

5 run days per week: 3 easy runs, 1 quality workout (tempo/intervals/marathon pace), and 1 long run. Recovery weeks (4, 8, 12) have reduced volume.

Week Easy Runs Quality Workout Long Run Weekly Total
14–5 mi × 320 min tempo10 mi~28 mi
24–5 mi × 36 × 800m at 5K pace12 mi~31 mi
35 mi × 325 min tempo14 mi~35 mi
44 mi × 3Easy 4 mi + strides8 mi~24 mi (recovery)
55 mi × 35 × 1 mi at 10K pace15 mi~36 mi
65 mi × 330 min tempo16 mi~38 mi
75 mi × 310 mi w/ 5 mi at marathon pace18 mi~40 mi
84 mi × 3Easy 4 mi + strides10 mi~26 mi (recovery)
95 mi × 36 × 1K at 5K pace18 mi~39 mi
105–6 mi × 312 mi w/ 8 mi at marathon pace20 mi~45 mi
115 mi × 335 min tempo16 mi~37 mi
124 mi × 3Easy 5 mi + strides12 mi~29 mi (recovery)
135 mi × 310 mi w/ 6 mi at marathon pace20 mi~43 mi
144–5 mi × 325 min tempo14 mi~33 mi (taper starts)
153–4 mi × 34 × 800m relaxed10 mi~24 mi
163 mi × 220 min easy + stridesRace day — 26.2!~18 mi

Weeks 4, 8, and 12 are recovery weeks. Weeks 14–16 are the taper. The taper is when all your training comes together — trust the process and resist adding extra miles.

The Long Run: Building to 20 Miles

The long run is the cornerstone of marathon training. Two key 20-milers at Weeks 10 and 13 are your biggest workouts.

Understanding "The Wall"

The Wall (or "bonking") typically hits between miles 18–22. Your body stores roughly 2,000 calories of glycogen — enough for about 18–20 miles of running. After that, you rely on fat oxidation, which is slower and feels dramatically worse.

How to prevent or minimize the Wall:

Marathon Fueling Strategy

Before the Race (2–3 Hours)

Eat a carb-heavy meal you've practiced: oatmeal with banana and honey, bagel with peanut butter, or white rice with a little protein. Aim for 200–400 calories. Drink 16–20 oz of water. Sip a sports drink in the hour before the start.

During the Race

Total race fuel target: 30–60 grams of carbohydrates per hour (roughly 1 gel per 30–45 minutes).

After the Race

Eat whatever sounds good within 30–60 minutes. Your body needs carbs, protein, salt, and fluids. Chocolate milk, pizza, or a full meal all work. Continue hydrating throughout the day.

Pacing Your Marathon

The marathon punishes bad pacing more than any other distance. Even a few seconds per mile too fast in the first half can cost minutes in the second half.

Use the splits calculator to build your mile-by-mile plan, and the training pace calculator to confirm your goal pace from a recent race.

Common Marathon Training Mistakes

1. Starting the Race Too Fast

The single biggest mistake in the marathon. You will feel fantastic in the first few miles. You are not faster than you think — you're just fresh. Stick to your pace plan or you'll pay for it after mile 18.

2. Skipping Recovery Weeks

Weeks 4, 8, and 12 feel like you're losing fitness. You're not. Recovery weeks allow your body to absorb the accumulated training stress. Skipping them leads to overreaching, injury, and arriving at the start line overtrained.

3. Not Practicing Nutrition

Your stomach needs training just like your legs. If you haven't practiced eating gels while running, race day is not the time to start. Use every long run over 14 miles to rehearse your exact fueling plan.

4. Chasing Mileage Over Quality

Running 50 miles per week of junk miles isn't as effective as 40 well-structured miles with purpose. Each run in this plan has a specific role: easy runs for recovery and aerobic base, quality sessions for fitness, long runs for endurance.

5. Training Through Pain

In a 16-week plan, you cannot afford to lose weeks to injury. If something hurts beyond normal muscle soreness, take an extra rest day or cross-train. It's better to arrive at the start line slightly undertrained than injured.

Sample Week: What Training Looks Like

Here's an example of Week 7 (the first 18-miler week):

Day Activity
MondayRest
Tuesday5 mi easy run
Wednesday10 mi total: 2 mi warm-up → 5 mi at marathon pace → 3 mi cool-down
Thursday5 mi easy run
FridayRest or cross-train (pool, bike, yoga)
Saturday5 mi easy run
Sunday18 mi long run at easy pace (practice fuel at miles 5, 10, 15)

The Taper: Weeks 14–16

The taper is the most mentally challenging part of marathon training. After months of building mileage, you suddenly run less. You'll feel sluggish, heavy, and convinced you're losing fitness. This is normal and expected.

During the taper, focus on sleep, nutrition, and hydration. These contribute more to race-day performance than extra training at this point.

After the Marathon: Recovery

The marathon takes a real toll on your body. Allow proper recovery:

Once recovered, use the race time predictor to plan your next goal. See what counts as a good marathon time for age-based benchmarks.

Related Tools & Charts

Marathon Training FAQ

How long does it take to train for a marathon?

16–20 weeks is standard if you're already running 25+ miles per week. If you're starting from a 10K base, plan 6–8 months total: build to half marathon fitness first, then begin marathon-specific training. First-time marathoners should not compress below 16 weeks.

Do I need to run 26.2 miles in training?

No. Most training plans peak at 20 miles. The extra 6.2 miles on race day are covered by your taper (which leaves you rested), race-day adrenaline, and the cumulative effect of months of progressive training. Running 26+ miles in training significantly increases injury risk.

What's a realistic goal time for a first marathon?

Take your half marathon time and multiply by 2.1–2.2. A 2:00 half marathon predicts a 4:12–4:24 marathon. Use the race time predictor for a more precise estimate. For your first marathon, the only goal that matters is finishing. You can chase time targets later.

What is "the Wall" and how do I avoid it?

The Wall is the dramatic slowdown between miles 18–22 caused by depleted glycogen (stored carbohydrate). You prevent it by: (1) carb-loading for 2–3 days before the race, (2) fueling with gels every 4–5 miles during the race, and (3) not going out too fast. Runners who fuel properly and pace conservatively either avoid the Wall or experience a much milder version.

How many gels should I take during a marathon?

Plan for 4–5 gels: at miles 5, 9–10, 14–15, 19–20, and optionally 22–23. Aim for 30–60 grams of carbohydrate per hour. Always chase gels with water, not sports drink. Practice this exact protocol during your long training runs.

What if I miss a training run?

One missed run is nothing — don't try to make it up. Move on. If you miss a long run, do a slightly shorter one next weekend and resume the plan. If you miss a full week due to illness or injury, repeat that week's schedule. Consistency over 16 weeks matters much more than any single workout.

Disclaimer: Marathon training places significant demands on your body. This plan is designed for healthy adults with an established running base. Consult a doctor before beginning marathon training. This content is for informational purposes only and not a substitute for professional coaching advice.