Half marathon training
How many weeks do you need to train for a half marathon?
Last updated
The StrideSheet half marathon planner supports 8 to 16 weeks, but the right length depends on your starting point. Count back from your race date, enter your current long run and inspect the resulting progression. A 12-week schedule is a useful worked example; the tool cannot confirm that a particular length is suitable for you.
For general information only, not professional advice. Check the official sources below. Use your own judgement and speak to a qualified professional, such as your doctor, before you act.
What should determine the number of weeks?
Your available time and current running are the starting inputs. A shorter schedule gives the tool fewer build weeks between your current long run and its nominal peak. More weeks spread that underlying progression across more dates.
The selectable 8 to 16-week range is a product limit, not an official recommendation for every runner. The tool does not ask about your health, previous injuries or recovery, and choosing a longer schedule does not guarantee readiness.
When does a 12-week plan begin?
For a race on Sunday 25 April 2027, a 12-week plan begins on Monday 1 February. The Monday of race week is 19 April; counting back 11 weeks gives the first Monday. The race is the final session.
Select 3 to 5 runs per week and check the fixed weekdays in the output. If your race falls earlier in the week, the final week contains only sessions that fit before it, plus the race itself.
How does the long run progress?
Use the same 25 April race date, 12 weeks, 4 runs per week and a current long run of 3 miles. The tool returns these selected long-run targets:
| Week | Long run | Phase |
|---|---|---|
| 1 | 3 miles | Build |
| 2 | 4 miles | Build |
| 3 | 5 miles | Build |
| 4 | 5 miles | Cutback |
| 5 | 7 miles | Build |
| 8 | 8 miles | Cutback |
| 10 | 12 miles | Build |
| 11 | 9 miles | Taper |
| 12 | Race | Race week |
World Athletics gives the race distance as 21.0975 km. The 12-mile training target in this example is a site planning rule; it does not change the race distance.
Where do cutback weeks and taper fit?
The underlying target rises linearly towards 12 miles or 20 km. Every fourth build week reduces its calculated value to 80%, then distances round to half a mile or one kilometre. A cutback can therefore be the same length as the previous week's rounded long run, as weeks 3 and 4 are here.
The final two weeks are marked as taper. The penultimate long run is 75% of the nominal peak, giving 9 miles in this example; the final long run is replaced by the race.
Some plan lengths end their build on a cutback and do not reach the nominal peak. The result explains the highest scheduled training long run. The 12-mile and 20-km targets are separately specified, rather than exact unit equivalents.
What should you check before following it?
Check the opening long run, run days, cutbacks and race-week dates against your own circumstances. Other sessions are easy runs with one optional steady session during build weeks; their distance or duration is yours to choose. Save PDF, Print or download the all-day calendar entries to review the complete schedule.
The official activity sources below describe general activity for health. They do not establish an ideal half marathon preparation length or endorse these exact targets. If you need an individual training decision, discuss your fitness and health with an appropriate qualified professional.
Make your own result
Use your own dates, distances or times in the half marathon training plan generator.
Open half marathon training plan generatorA few useful answers
Sources
- Centers for Disease Control and Prevention: Adult Activity: An Overview
General adult physical activity guidance. Does not prescribe the exact workouts or progressions in these tools.
- UK Chief Medical Officers: UK Chief Medical Officers' physical activity guidelines
General physical activity guidance; these tools' training rules are planning rules, not clinical prescriptions.
- World Athletics: Half marathon (discipline page)
Half marathon distance: 21.0975 km, exactly half a marathon.
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StrideSheet team
We build free running tools: training plans built to your race date, pace bands and race-day plans. Our plans follow published training principles and are a guide, not medical advice.