Marathon Training Plan: 16 Weeks, Week by Week

Why 16 Weeks?

Sixteen weeks is long enough to raise your weekly volume safely, fit in a few lighter weeks, and still leave two weeks to taper. If you already run regularly, it is a comfortable build-up. If you are starting from very little running, give yourself more time, or run a half marathon first.

Shorter races need less time. A common default is 12 weeks for a half marathon and 8 weeks for a 10K. The structure below works the same way for those distances, just with shorter phases.

The Five Phases

Every week in a good plan has a job. This is how the 16 weeks are split in the HEUMIN app:

Base (weeks 1 to 5)

Almost all running is easy. That can feel too slow, but easy running is what builds the heart, blood vessels and muscle endurance a marathon depends on. Your long run grows a little each week. One or two short sessions of strides or relaxed faster running keep your legs used to a quicker rhythm.

Build (weeks 6 to 10)

The long run keeps growing and the plan adds running at or near marathon pace, often in the second half of a long run or as a steady mid-week session. A tempo session at a comfortably hard effort builds the ability to hold pace when you are tired.

Peak (weeks 11 to 13)

These are the biggest weeks. The long runs reach their longest, often around 30 to 32 km for many runners, and include stretches at race pace. This is also the time to rehearse race day: your shoes, your kit, your breakfast and your fuelling on the run.

Taper (weeks 14 and 15)

Volume comes down, but intensity stays. You still run some race-pace sections and short faster efforts, just less of everything. Many runners feel restless or sluggish in the taper. That is normal. The fitness is already there; the taper lets the fatigue fade so it can show.

Race week (week 16)

A few short, easy runs with a little race pace to stay sharp. Sleep, eat well, lay out your kit early and resist the urge to test your fitness.

Two Rules That Keep You Healthy

Never more than about 10 percent extra a week

Weekly volume should grow gradually. A common guideline is to add no more than about 10 percent per week. Muscles adapt faster than tendons and bones, so a big jump can feel fine for a week and then turn into an overuse injury.

A lighter week every fourth week

In base and build, every fourth week drops back. These cutback weeks let the training sink in, and they give you a buffer for the weeks when life gets in the way. In the plan above, weeks 4 and 8 are the lighter ones.

Setting Your Paces From a 5 km Time

The simplest honest starting point is a recent 5 km time, run hard on a flat course. From it you can predict your times at longer distances with the Riegel formula:

For a runner with a 25:00 5 km, that gives roughly:

Treat the marathon prediction as a ceiling, not a promise. It assumes you have done the long-run training for the distance, and many first-time marathoners finish slower than Riegel predicts. If in doubt, start the race a little slower than your predicted pace.

Your easy runs should be clearly slower than marathon pace, often 60 to 90 seconds per kilometre slower. If you cannot talk in full sentences, slow down.

Target Time or Just Finish?

If you have a finish time in mind, your plan should include regular running at that pace, so it feels familiar on the day. If your goal is simply to finish strong, the plan can focus on easy volume and long runs, with less pressure on pace. Both are valid goals. A first marathon is a big achievement whatever the clock says.

How Many Days a Week?

You can prepare for a marathon on three to six running days a week. Three days works for newer runners if every run counts: one easy run, one quality session and the long run. Four or five days gives you more easy volume, which is where most of the fitness comes from. Six days suits experienced runners with time to recover. Put the long run on Saturday or Sunday, when you are not rushing.

Eating for Marathon Training

As the weeks grow, so does the energy you burn. Under-eating is a common reason runners feel flat in the build and peak phases.

• Carbohydrates are your main fuel. Eat more on long-run and session days, and a carb-rich meal the evening before your long run.
• Practise fuelling on long runs. Runs over about 90 minutes are the place to test gels, drinks or snacks, so race day holds no surprises for your stomach.
• Carb loading before the race. Sports nutrition guidelines suggest around 10 to 12 g of carbohydrate per kg of body weight per day for the 36 to 48 hours before a race longer than 90 minutes. In practice that means simple, familiar carbs like rice, pasta, bread and potatoes, with less fibre than usual.
• Protein for recovery. Spread it over the day, including a portion after your long run.

Not sure where your intake sits? Our guide on how many carbs you need per day and the TDEE calculator are good starting points.

Common Mistakes

• Running every run too fast. Easy days that are not easy make the hard days worse.
• Chasing missed runs. If you miss a few days, pick the plan back up where you are. Do not cram the missed kilometres into the next week.
• Skipping the taper. One last big long run in week 15 will not make you fitter by race day. It will make you more tired.
• Trying something new on race day. New shoes, a new gel or a new breakfast belong in training, not at the start line.

This article is general training information, not medical advice. If you have a health condition or an injury, talk to a doctor before you start a new training plan.