12 Week Half Marathon Training Plan

A 12-week half marathon plan that fits your running days, level and goal time.

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The 12-week half marathon training plan is a free tool that builds a complete week-by-week running schedule for a 21.1 km (13.1 mile) race. You choose your runs per week, your level, and optionally a goal time and race date, and it produces every run from the first easy day to the final taper. It runs entirely in your browser, so nothing you type is uploaded or stored on a server, and there is no account or sign-up. The page is preset to 12 weeks, which gives 10 build weeks and a 2-week taper. You can also choose any length from 8 to 20 weeks. Each week shows its phase, its total distance, and the pace or effort for every run. The plan is a training aid, not medical advice.

12 week half marathon training plan example

How to use the 12-week half marathon training plan

Check that Race is set to half marathon.
Leave Plan length at 12 weeks, or change it. For a half marathon you can choose between 8 and 20 weeks.
Pick Runs per week: 3, 4, 5 or 6 days.
Pick Level: Beginner, Intermediate or Advanced.
Optional: enter a Goal time, such as 2:30:00. This gives each run a pace range per mile or km. Leave it blank to see effort instead, such as “easy, conversational effort.”
Optional: enter a Race date. Each run then gets its date, and the race falls on that day. Week 1 starts on a Monday. Without a race date, long runs fall on Sunday.
Choose Units: miles or km.
Read the summary line first, then the training paces box if you entered a goal time, then the weekly boxes, which run Monday to Sunday.

Print prints only the plan. Download PDF saves a text PDF of the whole plan, made in your browser. Copy link works because your settings are kept in the page address, so the link opens the exact same result. Your miles or km choice is remembered in this browser. The 12-week length is already set, so you can skip step 2 for a full plan. Changing runs per week, level, goal time or race date rebuilds the whole plan from your inputs, so every week and every pace updates together.

Is 12 weeks enough to train for a half marathon?

Twelve weeks can be enough for a half marathon if you already run regularly, and it is the length this page is preset to. The tool divides those weeks into 10 build weeks and a 2-week taper, which is the taper length it uses for a half marathon. The build weeks split into phases: the first 40% (about four weeks) is base, with easy runs, strides and hill repeats; the next 40% (about four weeks) is build, with tempo runs and intervals; and the last 20% (about two weeks) is race-specific, with race-pace running. The taper then reduces the load before race day.

The length of the longest run depends on your level. In the tool’s intermediate example (4 runs a week, goal 1:45:00), the peak week is 29 miles (46.5 km) and the longest run is 11.5 miles (18.5 km). In the beginner example (3 runs a week, goal 2:30:00), the peak week is 17.5 miles (28 km) and the longest run is 8 miles (12.5 km). Two rules shape every week: hard sessions such as hills, tempo, intervals and race pace are never placed the day before or after the long run, and easy runs are at least 3 km.

What do the cutback weeks do?

Cutback weeks are lighter weeks that give your body time to recover from the training before them. In this plan, every fourth week is a cutback week, so weeks 4 and 8 are cutbacks. Each one is set at about 80% of the volume of the week before it. The tool marks them in the plan so you can see them at a glance.

Cutback weeks work with another rule: no week is more than 10% above the largest week before it. Together, these two rules make the plan rise in steps rather than in sudden jumps. A cutback week is not the taper. The taper is the final stretch before race day, while cutbacks happen during the build.

Can I change the plan length on this page?

Yes. Plan length is a setting, and a half marathon plan can run from 8 to 20 weeks. Changing it rebuilds the whole plan, so a longer plan spreads the same rules over more weeks.

What paces does a 12-week plan use?

The worked example for an intermediate runner with a 1:45:00 goal and 4 runs a week gives an easy pace of 9:33 to 10:48 per mile, a threshold pace of 7:44 per mile and a goal race pace of 8:01 per mile. Enter your own goal time to get paces that match your level.

Frequently asked questions

When should I start a 12 week half marathon plan?

Enter your race date and the plan counts back from it, so that week 1 starts on a Monday and the race falls on race day. Without a race date, the plan starts next Monday. Choose a race date about 12 weeks away if you want a full plan.

Can beginners use a 12 week plan?

Yes. Set the level to Beginner and choose 3 runs a week. In the tool’s beginner example, the plan has 36 runs, a peak week of 17.5 miles (28 km), and a longest run of 8 miles (12.5 km). Build up gradually, and ask a doctor before you start if you have a health condition.

Can I add the plan to my calendar?

Yes. Add to calendar (.ics) creates one all-day event for each run, for Google Calendar, Apple Calendar or Outlook. If you do not enter a race date, the events start next Monday. Saving plans, moving missed runs, calendar sync and reminders are coming soon.

Do I need a goal time?

No. The goal time is optional. Without one, each run is described by effort, such as “easy, conversational effort.” With one, each run gets a pace range per mile or km, and the training paces box shows them. The paces are calculated from your goal time using the Daniels & Gilbert (1979) equations.

What happens if I change the runs per week or level?

The whole plan is regenerated. The plan is built by code from your inputs, not copied from a coach or a book, so changing the number of weeks, days or the level changes every week.

Can I use the plan commercially, for example with runners I coach?

Yes. Plans, PDFs and calendar files you make here are free to use for any purpose, including handing them to runners you coach, with no credit needed. You may not copy the generator or the site itself; see the terms.

Marathon training plan: Use this when your target is 42.2 km rather than a half marathon.
Half marathon training plan: Use this to set your own plan length and start date for a half marathon.
5K training plan: Use this if your next race is 5 km.
10K training plan: Use this if your next race is 10 km.
Beginner running plan: Use this if you are new to running and want a gentler start.
Training pace calculator: Use this to get training paces from a recent race result.
Pace chart for this race: Use this to see split times for each kilometre or mile of a half marathon.
Pace band: Use this to plan your pace across a race, with splits you can carry on a card.
Methodology: formulas and plan rules: Use this to read the formulas and rules behind every plan.

Updated October 2026