How to Train for a Marathon: The 18-Week Plan, the Wall and the Taper

You signed up, or you're about to. And somewhere between the confirmation email and your first long run, 26.2 miles started to feel like a distance other people run.

Maybe you've already started once and drifted. A great first month, then a missed long run, then another, and by the time the race came around the training plan was a document you avoided opening. That isn't a character flaw. Most plans hand you a table and leave the hard part, showing up week after week for four months, entirely to you.

This guide explains what a marathon asks of your body that shorter races don't, how long you realistically need, and what each phase of training is for. Once you know why each week looks the way it does, the plan gets much easier to keep.

How Long Does It Take to Realistically Train for a Marathon?

It takes about 18 weeks of marathon-specific training if you already run 15 to 20 miles a week, and six to twelve months if you're starting from less. The marathon plan isn't what takes time. Building the easy weekly base it starts from is.

The reason not to rush is injury, and newer runners carry more of it. A 2015 meta-analysis by Videbæk and colleagues in Sports Medicine found novice runners picked up 17.8 injuries per 1000 hours of running, more than twice the 7.7 of recreational runners. First-time marathoners in a New York City Marathon trial reported a major injury in 8.9 percent of cases and a minor one in 48.5 percent (more on that trial in the strength section). If you're starting from zero, a 5K training plan for beginners is the right first block, and the marathon comes after.

The Marathon Training Plan, Phase by Phase

Every marathon training program worth following has the same skeleton: a slow rise in weekly distance, one long run a week that grows, a little marathon-pace work, and a taper. Here's that skeleton for a first-timer whose goal is to finish strong, laid out as four phases rather than 18 separate weeks:

Run four or five days a week: one long run, one run with some marathon-pace miles in the build and peak phases, and easy runs for the rest. Every third or fourth week, drop the weekly distance by about a quarter so your body can absorb the work.

The evidence supports building volume rather than chasing speed. Doherty and colleagues (2020), in a meta-regression of 85 studies and 137 groups of runners published in the Journal of Science and Medicine in Sport, found that average weekly distance, runs per week, the number of runs of 32 kilometers or more and the length of the longest run each tracked faster finish times. Tanda (2011), following 22 runners through 46 marathons in the Journal of Human Sport and Exercise, could predict finish time to within about four minutes from just two numbers over the final eight weeks: average weekly distance and average training pace.

Those numbers are a template, not a trial result. If a week goes badly, repeat it rather than skipping ahead.

Half Marathon to Marathon Training Plan

If you've run a half marathon in the last few months and kept running about 20 miles a week since, you already have the base, so you can start the table above at week 4 or 5 instead of week 1. What changes is everything past mile 13: the long run keeps climbing, fueling becomes mandatory rather than optional, and the taper gets longer. Our half marathon training plan covers the 12-week build to 13.1 and the evidence on how fast to raise weekly mileage. This page picks up where that distance stops.

The Long Run and the 20-Mile Question

The long run is the session that turns a half marathoner into a marathoner. It builds the fuel stores, the leg durability and the patience the second half of the race asks for.

• Run it slow. Aim for 60 to 90 seconds per mile slower than your goal marathon pace. If you can't speak in full sentences, slow down.
• Cap it by time. Past about three to three and a half hours, a long run adds more fatigue than fitness. Slower runners can stop at 18 miles and lose nothing.
• Peak three weeks out. Put your longest run about three weeks before race day so the taper has room to work.
• Rehearse the race. Eat and drink on every long run from the build phase onward, and run the last few miles of one or two peak long runs at goal pace.

Fatigue changes your stride late in a long run, and a slightly quicker, shorter step reduces the load each landing puts on the knee. Our review of running cadence research covers how much to change it and who benefits most.

Strength and Mobility for Marathon Runners at Home

Strength training makes running cheaper, but a token routine won't keep you injury-free. Two studies show both halves of that.

The upside is efficiency. Balsalobre-Fernández and colleagues (2016), in a meta-analysis of controlled trials in the Journal of Strength and Conditioning Research, pooled 93 competitive distance runners and found a large improvement in running economy after 8 to 12 weeks of strength training two or three times a week, using two to four lower-body exercises plus jumps. Better economy means each mile costs less energy, which matters most in the final hour of a marathon.

The caution comes from first-timers. Toresdahl and colleagues (2020), in Sports Health, randomized 720 first-time New York City Marathon runners to a 10-minute strength routine three times a week, delivered by written and video instruction, or to no program. Overuse injuries that stopped people finishing were almost identical: 7.1 percent with the routine and 7.3 percent without it. A short self-directed routine wasn't enough to change injury rates. Progressive strength training, where the load keeps rising, is the version with the performance evidence behind it.

A practical version with dumbbells and bodyweight:

• Reverse lunges or split squats: 3 sets of 8 per leg, adding weight as they get easy.
• Single-leg Romanian deadlifts: 3 sets of 8 per leg, for the hamstrings and hip stability.
• Single-leg calf raises: 3 sets of 12 to 15, slow on the way down. Your calves take a heavy load on every stride.
• Step-ups: 2 sets of 10 per leg onto a sturdy step or bench.
• Side planks and dead bugs: 2 to 3 sets each, for a trunk that holds its shape when you're tired.
• Mobility: five minutes for the hip flexors, calves and ankles after easy runs.

Do it twice a week in the base and build phases, once a week at peak, and keep only light sessions in the taper. Put strength on the same day as a harder run so your easy days stay easy.

FitCraft isn't a running app, and it won't write your marathon plan. Where it fits is this part of the week. Its strength workouts use dumbbells and bodyweight, it has mobility and yoga sessions, an AI coach demonstrates each exercise on an interactive 3D model, and the workouts adjust as you progress. If you're comparing tools for the strength side of training, our roundup of the best strength training apps sets the options side by side.

Why Runners Hit the Wall at Mile 20

Hitting the wall is a fuel problem. Your muscles and liver store a limited amount of carbohydrate as glycogen, and at marathon pace many runners use most of it before the finish.

Rapoport (2010), modeling marathon metabolism in PLOS Computational Biology, estimated that more than two-fifths of marathoners experience severe, performance-limiting glycogen depletion. When it happens depends on muscle mass, glycogen stores and pace, which is why the same race leaves one runner fine and another walking.

Real race data shows how common it is. Smyth (2021), analyzing more than 4 million marathon records in PLOS ONE, found that 28 percent of men and 17 percent of women hit the wall, usually after the 20-mile mark. Those who did slowed by around 40 percent compared with their earlier pace, for roughly the last 10 kilometers.

This is also why carbohydrate loading is a marathon tool and not a 10K one. Hawley and colleagues (1997), reviewing the loading research in Sports Medicine, found that topping up muscle glycogen did nothing for moderate runs of 60 to 90 minutes, but postponed fatigue by about 20 percent in events lasting longer than 90 minutes and improved set-distance performance by 2 to 3 percent.

Fueling and Pacing So You Don't Hit the Wall

Two habits keep most runners off the wall: eating during the race and starting slower than feels necessary.

• Eat early and often. Burke and colleagues (2011), in their review in the Journal of Sports Sciences, set 30 to 60 grams of carbohydrate an hour for long events and up to 90 grams an hour for events lasting longer than about two and a half hours, which covers most marathoners. Start within the first 30 to 45 minutes and take something every 20 to 30 minutes.
• Train your gut. High intakes upset an untrained stomach. Use every long run from the build phase onward to practice the exact gels, chews or drinks you'll use on race day, building up toward your target amount.
• Load sensibly. For the last two or three days, make carbohydrate the bulk of every meal and ease off fiber and fat. It's a change in proportion, not a feast.
• Pace evenly. Run the first half no faster than goal pace. Smyth's data found the wall was more common in the three years either side of a recent personal best, 36 percent against 23 percent in earlier years, which is when many runners are racing for a time.

The Taper: Three Strict Weeks Beat a Loose Two

The taper is where weeks of fatigue lift and the fitness shows up. For marathoners, the best evidence favors three weeks of steadily falling volume.

Smyth and Lawlor (2021), in Frontiers in Sports and Active Living, analyzed the training of more than 158,000 recreational marathoners. Strict tapers, where volume dropped every week, beat relaxed ones, and tapers of up to three weeks beat shorter ones. A strict three-week taper was linked to a median finish 5 minutes 32 seconds faster, about 2.6 percent, than a minimal taper. Most runners, 64 percent, tapered less strictly than that, and women gained more from a given taper than men.

The shape of the cut matters too. A meta-analysis of competitive athletes by Bosquet and colleagues (2007) in Medicine & Science in Sports & Exercise found the best results came from reducing training volume by 41 to 60 percent while keeping intensity and frequency the same. In practice, keep running on your usual days, keep a few short marathon-pace segments, and shrink everything else.

Is a Marathon Safe? The Real Risks

For most healthy, well-prepared runners, yes. The risks are real but small, and most of them are about preparation.

• Not finishing. Across the research groups in Doherty's meta-analysis, 7.27 percent of starters didn't finish.
• Overuse injury. In the New York City trial, 52 of 64 major injuries were overuse injuries, and 20 of those were bone stress injuries. Gradual mileage and cutback weeks are the main protection.
• Cardiac events. Kim and colleagues (2012), in the New England Journal of Medicine, tracked 10.9 million US marathon and half marathon runners over a decade. Cardiac arrest happened at 1.01 per 100,000 marathon participants against 0.27 in half marathons, mostly in men and mostly from underlying heart disease. Bystander CPR was the strongest predictor of survival.

That last point is why a check-up before your first marathon is worth it, especially for men, anyone over 40 and anyone with a family history of heart disease.

The Bottom Line

Training for a marathon means about 18 weeks on top of a running base: a gradual build in weekly distance, a long run that reaches 18 to 20 miles, carbohydrate practiced on every long run, and a strict three-week taper. Strength work twice a week makes the miles cheaper, as long as the load keeps rising.

Four months is a long time to stay consistent, and consistency is what the research rewards. If you string the weeks together, the finish line takes care of itself.