12-week half marathon training plan

Pick the level that matches what you do now, not what you'd like to run on race day. If you're between two, take the lower one: you can always run the easy days a bit longer.

Not there yet? Spend a few weeks building up first, for example with our AI running coach or by adding 1 km to your longest run each week.

Every session in this training plan uses one of five efforts. Find your own paces with the running pace calculator or the VDOT calculator, using a recent race. No recent race? Start from the heart rate and effort columns. Your max heart rate is best taken from a hard effort, because age formulas can be well off.

Heart rate lags behind in short efforts, so use pace or feel on anything under 5 minutes. On hills and hot days, go by effort and let your pace drop.

Three ideas carry the whole schedule:

• Mostly easy. About 80% of your running is easy. It feels too slow at first, and it's what lets you run the hard sessions well and stay healthy.
• Build slowly. Your long run grows by about 10% a week at most. Every fourth week is an easier week with less distance.
• Get specific late. Early sessions build speed and threshold. From week 9 you practise your half marathon pace, so race day feels familiar.

Each table lists the runs in order. Put them on the days that suit you, with these three rules:

• Long run on the day you have the most time, usually Saturday or Sunday.
• At least one easy day or rest day between the session with efforts and the long run.
• At least one full rest day a week. Beginners and intermediate runners do well with two or three.

Start every session with efforts with 10 to 15 minutes easy, and finish with 5 to 10 minutes easy. That running is included in the distance.

Four runs a week. Your long run builds from 10 to 18 km. Strides are relaxed, fast runs of 20 seconds with a full walk back.

Four runs a week with one proper session. Your long run builds from 12 to 20 km.

Five runs a week with two sessions. Your long run builds from 15 to 20 km.

In week 11 your distance drops by about a third, and in race week it drops again. You keep a little race pace in the schedule so your legs stay awake. Many runners feel flat, restless or heavy in these weeks. That's normal and it says nothing about your fitness. Don't add extra runs to feel better: the fitness you have is already there, and the rest is what lets you use it.

In race week, sleep as much as you can and eat normally. Plan your fuelling and pacing with the race nutrition calculator and race time predictor, and don't try anything new on the day.

Life gets in the way of every training plan. Use these rules:

• Missed one easy run: let it go.
• Missed the session with efforts: do it later this week if you still have a day between it and the long run. Otherwise skip it.
• Missed the long run: do it within the next two days if you can, and take an easy day after it. Otherwise pick the plan back up at the next week and don't try to catch up.
• Missed a full week: repeat the week before you stopped, then carry on.
• Sick: rest until your symptoms have gone, then restart with a few easy runs. Fever or symptoms in your chest mean no running, and see a doctor if you're worried.
• Tired for several days, poor sleep or low HRV: make the next session with efforts an easy run. One easier day costs you nothing.
• Pain that changes how you run: stop, and have it checked. Running through it rarely ends well.