How Long to Train for a Marathon: An Individualized Approach

Have you ever wondered when to start training for a marathon? Do you need 16 weeks, 24 weeks, a year?

You will in no way be surprised to hear that I’m going to say there are a number of factors that determine how long marathon training takes for each runner. I’m going to try to break down some of those common things today and give you guidance on where to start and what to do from there.

One of the things I take in to account is running history. Newer runners should allow a much longer time frame to build up to the marathon distance. This is because the muscles, tendons, ligaments and joints need time to adapt to the impact of running.

Many times we can make big gains in our aerobic fitness quickly, but that doesn’t mean the body is fully adapted.

“Although you might be able to aerobically handle a marathon, it doesn’t mean these connective tissues and bones have adapted sufficiently to handle the stress,” says Janet Hamilton, an exercise physiologist.

Marathon training timelines are about both the physical and mental adaptations required.

There’s a reason lots of folks say “I don’t even like to drive that far.” 26.2 miles is a serious distance and needs to be treated as such…but also, it’s a lot of fun!

How Long to Train for a Marathon?

The most common training plans on the Internet or from a running book are 16-20 weeks. The amount of time that you need for training could fall squarely in that very normal range or you might need less or more time.

Coach Amanda at finish line after pacing athlete Jodi to first marathon.

Most marathon training plans are assuming a few things:

  • Current baseline of fitness that allows you to complete 20 miles per week
  • At least a year of consistently running without injuries
  • Understanding your current availability to put in the required mileage
  • A too short training period create risk injury (which means no race!)

Everyone is different, which is why there are so many training plans and why coaches help develop custom schedules.

20 weeks of training is roughly 4.5 months, which provides sufficient time to increase your mileage steadily without any big jumps. This is often referred to as the 10% rule of training, which helps to prevent injuries.

While you will be doing pieces of strength, intensity, volume building throughout training you could think of it as being broken down in to these segments. Where each uses the previous weeks of training to move you closer to your goal.

Periodized Marathon Training Plan

A marathon training program is designed to follow a periodized model of training. This takes you from the least specific work to the most specific, so that you are slowly building the appropriate fitness for your marathon goal.

Weeks 1-4 – Base

Base building time to begin slowly ramping up your total mileage. Ensuring you have built the necessary core, hip, glute strength to prevent injuries throughout training. You may have a few speed workouts during this phase depending on your current level of fitness, particularly running strides.

Starting to get in the rhythm of having 1 long run per week and what your schedule will look like. Learning that a slow jog and easy runs are your best friend for increasing endurance.

Weeks 5-8 – Strength

In a 10 week plan, we are continuing to work on building up the base for most runners. Slowly increasing to longer distances, while also starting to add in more strength workouts.

That includes both lifting with weights and workouts like hill sprints, hilly routes and short tempo runs. Cross training can be as short as 20 minute full body lifts 2 days per week to 3 days of lifting and pre-run core workouts. Again, it’s going to depend on the previous training experience.

Starting to practice recovery runs and full rest days to maximize training.

Weeks 9-12 – Volume

Now we’re starting to move in to a period of honing in on the abilities you need to run a marathon. We aren’t yet doing super specific speed work, but we are now combing more volume with intensity.

Intensity could include speed sessions with 5K to marathon pace intervals. We keep in the shorter speed work to continue working those fast twitch fibers, while we are increasing total work volume.

Starting to adjust lifestyle around the time needed to train and recover. More food prep to get enough carbohydrates, more eating to recover, more foam rolling, more planning your schedule and pondering what you’ve gotten in to all take time.

Full marathons require a different level of mental training. Now is when you start practicing your mantras and listening to all the recommendations from your coach to keep pushing through those “can I do it?” fears.

when to start marathon training

Weeks 13-16 – Intensity

At this point, you are starting to hit some of your longest runs. For new runners that could mean 16 miles or even up to your first 20 miller. You’ll be adding more workouts with race pace miles, while maintaining strength training workouts and volume.

This is the point where marathon training burnout can set it. So it’s important to have a plan that works for your life, your goals and your current level of fitness.

Starting to really see the progress in your training. Dialing your gear for longer distances and working on nailing your long run fueling plan from the right energy gels to hydration. Understanding how your stomach reacts.

Weeks 17-20 – Specificity

This final section provides a couple weeks of very race specific training, which could mean final long runs of 20-22 miles for newer runners. Or it could be a long run with 1/2 at marathon pace, or progression to faster than marathon pace for experienced runners.

Peak week will be your highest weekly mileage and most difficult long run.

Then you will transition in to the final two weeks of the plan, which are taper.

Taper it NOT optional, it’s part of training. You’ll need to get out of your head about the reduced mileage, so learn how to do marathon taper the right way.

Can You Train for a Marathon in 3 Months?

It’s not unheard of for long time runners to build up to a marathon in 3 months with a 12 week training plan. This is because they maintain a consistent level of fitness year round, which allows them to dive in to race specific training with less total time needed.

In that scenario, an intermediate to advanced runners is skipping the 4-6 weeks of base building work because it’s simply part of their ongoing routine.

For runners in this category, the issue with starting training too early is that they will often peak too early. This means hitting their top level of fitness and readiness for the race.

This is exactly what happened to me leading up to the Chicago marathon. Knowing my own fitness, I should have pushed for a 16 week plan, but ended up on a 20 week plan where I hit my peak at week 16.

What happens if you don’t give yourself enough time to train for a marathon?

It’s not uncommon to have runners reach out for coaching when they realize the marathon is just 3 months away and they haven’t been putting in the work.

Sometimes we will agree to work with them, but others I will honestly tell them I don’t feel we’d be doing them a service to try and force the marathon.

  • Potential for injury during training and the race increase
  • Frustration from not being able to complete the assigned workouts is high
  • Disappointment with how race day goes leads to no longer running

How long to train for a marathon

How Long Should a Beginner Train for a Marathon?

On the flip side, we often coach runners who need a full year to build up to the first marathon distance.


As a running coach, I want to see people with at least a year of consistent running under them before tackling the marathon. 100% you can use our Couch to Marathon plan which is 24 weeks. But you’ll notice all over that training plan, I say it’s doable and I’ll cheer you on…but not my preference.

  • If you’ve been running consistently for a year, checkout a 20 week marathon training plan
  • If you’ve recently run a half marathon feeling strong, checkout a 16 week marathon training plan
  • Starting from scratch? Consider spending a year focusing on shorter distances from 10ks to half-marathons to build fitness and endurance.
  • Runners with a slower pace may also need more build time because we don’t want long runs to require too much time on feet, as that will delay recovery and compromise the next week of training.

Remember that you do not need to cover 26.2 miles in training! Taper means going in to the race with fresh legs. That plus the adrenaline give you an incredible boost.

Whew that was a lot of information, but I hope now you have a better answer to how long does it take to train for a marathon!

If you’re looking for more marathon training tips, we’ve got you covered:

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