How long does it take to train for a marathon?

Mental adaptations from marathon training

There’s no two ways about it; training for a marathon is a huge physical and mental undertaking.

So not only can you expect to see huge positive changes to your body and overall fitness, but tackling a marathon training programme will also bring about plenty of benefits to your mental health, too.

Runners frequently report improvements in mood and increased mental resilience and toughness while training for a marathon; plus, it’s great for habit-building and developing discipline. 

Your marathon training schedule will also teach you how to maintain focus and concentration to keep a steady pace, and learn to stay tough when the pain kicks in. 

Working out your ideal marathon training programme length

While the 16-20 week training period is a great baseline guide for many recreational runners, you might need to train for longer if you’re a complete beginner or can only commit to one or two runs a week.

Equally, if you’re already racking up 20+ miles a week and have been running for a long time, you might be able to shave weeks off that timeframe.

How long you need to train for a marathon depends on several factors.

Your general fitness levels

If you’ve not done much running before, but do play other sports and are generally fit and healthy, you might only need to add a couple of weeks on to the standard marathon training programme. 

However, if you’re starting from scratch and lead a very sedentary lifestyle, you’ll likely need to train for much longer to allow your body to adapt safely.

Your tendency to get injured

If you’re susceptible to niggles, aches and pains, or more serious injuries, you’ll probably need to factor in more rest days and more gradual increases in mileage to try and reduce the risk of any flare-ups. 

Giving yourself a few extra weeks to build up your fitness is a smart idea in case you have to take a week or so off to recover. 

Your job and lifestyle

How many runs you can commit to each week will have a big impact on the overall length of your training plan. 

If you have a stressful job with unpredictable hours (or shift work), caring responsibilities, or spend a lot of time travelling for work, give yourself more time to build your training and avoid the stress of feeling underprepared if you have to miss a run here and there. Read our guide on fitting marathon training around work for more tips on this.

Your running experience

Your running experience plays a big role in how long you should train for a marathon. If you’re already a regular runner with a solid fitness base, it’s easier to increase mileage and handle longer runs. 

But if you’re new to running or returning after a break, jumping straight into a standard plan can raise your risk of injury. In that case, a longer program that includes a base-building phase is a safer way to prepare for race day.

Use this handy guide below to work out roughly how long you might need to allow yourself to train for a marathon.

Your essential guide to the base-building phase for beginners

If you’re training for your first marathon, the initial stage, known as the ‘base-building phase’, will be one of, if not the most important part of your programme.

This block of training – usually over 6-12 weeks – will be crucial for developing musculoskeletal strength to reduce the risk of injuries before you begin your marathon training in earnest.

There are four key focuses to the base-building phase for beginners:

• Consistent mileage, allowing for very gradual increases in the time you’re running for and the miles you’re covering. 

• Aerobic development and adaptations within your cardiovascular system.

• Structural adaptation and strengthening your muscles, tendons, and bones.

• Movement quality and developing an efficient running technique. 

The goal of this phase is to reach a point where you can comfortably run three or four times a week, covering 10-15 miles across sessions lasting 20-50 minutes, before moving on to the standard marathon training programme.

You can also add cross-training (ideally non-impact cardio, such as swimming, cycling, or an elliptical machine) to further strengthen your aerobic and muscular endurance without putting too much stress on your joints. 

How to safely increase your mileage during marathon training

When you’re making brilliant progress and flying through your marathon training, the last thing you want is to be struck down by an injury.

So, it’s really important that you increase your mileage gradually, rather than making big incremental jumps from session to session.

There are two ways you can go about this.

Safely increasing your mileage: The 10% rule

As the name suggests, this is where you increase your running mileage by up to 10% each week until you reach your target distance. This is a safe, easy-to-follow method that suits all runners regardless of their experience.

Safely increasing your mileage: The equilibrium method 

More advanced runners might find the 10% rule too restrictive and instead choose to follow the equilibrium method, which allows you to increase your mileage by up to 25% and then stay at that level for around a month so your body has time to adapt.

Incorporating deload weeks into your marathon training

‘Deload weeks’, sometimes known as ‘down weeks’, are just that: it’s when you decrease your training load, giving your body a chance to rest and recover.

Science proves that recovery is where adaptations occur,  so deload periods should be a critical part of any endurance training plan. While you might not want to take a break, these scheduled rests will help you come back refreshed and even stronger for bigger mileage weeks.

There’s no hard-and-fast rule on how often you should take a deload week. The most common schedule is to take a down week every fourth week, but some marathon runners prefer to take one every six.

During a deload week, you should:

• Reduce your overall training volume by around 20%.

• Cut your longest run of the week down by 15-25%.

• Lessen the intensity of your sessions (for instance, by cutting out interval or tempo runs and just doing steady-state workouts).

• Add in one or two extra rest days.

Reducing the time you spend running will mean you’ll have some extra time on your hands, but don’t be tempted to fill it with extra gym sessions or other forms of exercise.  A deload week is a time for your body to rest, not just from running, but from all intense movement.

It’s a marathon – not a sprint

How long it takes to train for a marathon depends on several factors, which are personal to you and your experiences.

However, whether you’re following a standard marathon training plan or using your existing experience to prep in a shorter time, training for a marathon takes time, patience, and careful planning, and there are a few key principles that apply to every runner.

Consistency is important, but so is flexibility – life happens, and missing a session now and then is perfectly normal. A well-structured marathon training plan is long enough to accommodate small interruptions without derailing your progress.

It’s also essential to respect deload weeks. These recovery periods give your body the chance to adapt and grow stronger, and taking them seriously will make you a better, more resilient runner. 

Gradually increasing your mileage is another cornerstone of safe, effective training. Steady progression will help protect your muscles, joints, and connective tissue while building the endurance you need for race day.

Finally, use your long runs as opportunities to rehearse every aspect of the marathon experience, from pacing and marathon nutrition to hydration and mental strategies, so that when race day arrives, you can approach it with confidence.

By following our guide for how long to train for a marathon, you’ll give yourself the best chance of safely crossing the finish line and ticking off that bucket list goal.