Beginner Half Marathon Training Plan: A 12-Week Build

Here is the short answer. A beginner can train for a first half marathon in about 10 to 12 weeks. You need one thing first: the ability to run for 20 to 30 minutes without stopping. From there, the plan slowly stretches your longest run out to around 10 miles. That way, the last 5 kilometers of race day feel earned, not scary.

Week	Long run	Approx. weekly total
1	4 miles	~12 miles
3	5 miles	~14 miles
5	6 miles	~16 miles
7	7 miles	~19 miles
9	10K tune-up race	~19 miles
11	10 miles (peak)	~23 miles
12	Half marathon, 13.1 miles	Race day

What is a beginner half marathon training plan?

A beginner half marathon plan is a 10 to 12 week schedule. It stretches your longest run out to about 10 miles, step by step. It does not jump straight to big distances. It grows your weekly long run a little at a time. Easy runs and rest days fill the rest of the week.

A well-known example is the Hal Higdon Novice 1 plan. It runs 12 weeks. It has four run days, rest days, and one weekly long run (Hal Higdon). That long run peaks at 10 miles before race day. The table above follows the same shape. The long run grows slowly. Then it holds near its peak before the race. It does not climb right up to the finish distance.

If you have never run at all, this plan is not your starting point. Build a running habit first. Try couch to 5K or how to start running. Then come back here.

What base do you need before starting?

You need to run for about 20 to 30 minutes without stopping before you start. This small base protects you once your weekly mileage climbs.

Health bodies recommend adults build toward about 150 minutes of moderate activity a week (Garber et al., 2011). Add it slowly, not all at once. That level of steady activity is a fair sign of readiness. If you are well short of it, spend 4 to 8 weeks on your base first. It feels slower. But it is not wasted time. It is the floor the rest of your plan stands on.

Skipping the base is the biggest mistake beginners make. It is tempting to copy a 12-week plan from a friend. But your current running may be much smaller than theirs. Their base is not your base. Match the plan to you, not to them.

What does a realistic 12-week build look like?

A realistic build grows your long run by about a mile every one or two weeks. Then it holds near the peak before race day. Look at the table above. The long run rises from 4 miles in week 1. By week 11 it reaches 10 miles. Week 12 is the race itself.

Notice the plan is not a straight climb. Some weeks hold steady. Two weeks even swap the long run for a shorter tune-up race. This gives your legs a break from always adding distance. It lowers your injury risk while it still builds fitness.

The other easy runs during the week matter more than people think. Added together, they cover more distance than the long run alone. They build your aerobic engine, day after day. The long run gets the attention. The easy days do most of the quiet work.

How long should your longest run be before race day?

Your longest training run should reach at least 10 miles. Research suggests going a bit further can help even more. A study of 556 half marathon runners found that a longest run beyond 13 miles was linked to a faster finish time (Fokkema et al., 2020). The same study found that higher weekly volume and a longer long run were not linked to more injuries.

21 km+

longest training run linked to a faster half marathon finish, with no added injury risk (Fokkema et al., 2020)

That last point matters most. Many beginners avoid long runs out of fear of getting hurt. This study followed runners already signed up for a real race. It found the opposite of that fear. Runners who trained more, and ran longer long runs, did not get hurt more often than those who trained less. Smart, gradual buildup is the real difference, not the total distance alone.

Do not chase this number in week 1. Build to it slowly. A 10 to 11 mile peak long run, reached over 12 weeks, is what makes a 13.1 mile race day feel earned instead of scary.

How fast should your weekly mileage grow?

Your weekly mileage should grow in small, steady steps, not big jumps. A common guideline says to add no more than about 10% more distance a week. This is a rule of thumb, not a strict law.

A year-long study followed 874 novice runners (Nielsen et al., 2014). It found no clear difference in injury rates between small, medium, and large weekly jumps in distance. The authors pointed to about 30% growth per two-week block as a safer target than a strict 10% rule. What matters most is avoiding one huge jump. Do not double your long run after a missed week. Small, repeated steps beat one big leap.

What is a realistic first half marathon goal?

A realistic first goal is a time your recent training actually supports. It is not a number picked from a friend's result or an old race. Your fitness should set the target, not your hope.

Many beginners pick a goal first, then try to force their training to match it. It works better the other way around. Look at what your weekly runs and your longest run can support. Then set the goal from there. A goal inside your fitness is one you can chase with confidence. A goal far outside it often leads to a hard back half and a slow finish.

Is it okay to walk during a half marathon?

Yes, walking during a half marathon is fine, even for a well-trained beginner. Planned walk breaks do not mean you failed.

Many first-time half marathoners walk through water stops. Some walk short stretches near the end. One study of marathon runners tested a run-walk strategy against running the whole way (Hottenrott et al., 2016). The run-walk group had less muscle pain and fatigue. Their finish time was almost the same. That study covered a longer race. But the same idea holds for a half marathon. A short walk break at mile 10 can save your legs. It often leads to a stronger finish than pushing through pain.

Walk breaks work best when you plan them ahead of time. Decide before race day if you will walk through every water stop. A planned break is a strategy. An unplanned one is different. Cramping or sudden exhaustion usually means you started too fast, or skipped long runs in training.

How does PIRX set a fair half marathon goal for you?

PIRX reads your actual training and turns it into a number you can trust. A printed plan tells you what to run. It cannot tell you what you are ready to run on race day.

One-size-fits-all calculators use a single fixed formula on one input. They miss a lot. Maybe your long runs are strong, but your weekly frequency is low. Maybe your easy runs are too fast for real recovery. A fixed formula cannot see any of that. PIRX is a proprietary machine-learning prediction engine. It learns your training instead of guessing from one number. It scores five drivers behind your finish time: Aerobic Base, Threshold Density, Speed Exposure, Load Consistency, and Running Economy. For a first half marathon, two drivers carry the most weight: Aerobic Base and Load Consistency. They reflect your engine and your weeks of steady training.

PIRX turns those scores into a Projected Time with a Supported Range. Your goal comes from real data, not a guess. This is what makes PIRX different. A watch tells you what you ran. PIRX tells you what that training is actually worth on race day.

Want the bigger picture first? Start with the complete guide to predicting your race time. If a half marathon still feels far off, how long it takes to train for a 5K is a gentler place to start. Not sure your training matches your goal at all? See is my goal time realistic.

98%

validated prediction accuracy (PIRX users)

See your fair first half marathon target

Stop guessing your first half marathon goal from someone else's result. A generic watch algorithm treats a first-timer the same as a runner who has raced for years. PIRX does not. Connect your Garmin, COROS, or Strava in under 30 seconds. See your five performance drivers. Get a Projected Time built from your own training.

Sources

• Hal Higdon. Novice 1 Half Marathon Training Program. (12-week plan. Long run peaks at 10 miles before race day.)
• Garber, C.E. et al. (2011). American College of Sports Medicine position stand: quantity and quality of exercise. Medicine & Science in Sports & Exercise. (Adults should build toward 150 minutes of activity a week.)
• Fokkema, T. et al. (2020). Training for a (half-)marathon: training volume and longest endurance run related to performance and running injuries. Scandinavian Journal of Medicine & Science in Sports. (556 half marathon runners. A long run past 21 km was tied to a faster finish, with no added injury risk.)
• Nielsen, R.O. et al. (2014). Excessive progression in weekly running distance and risk of running-related injuries. Journal of Orthopaedic & Sports Physical Therapy. (874 novice runners. No clear injury difference across weekly jump sizes.)
• Hottenrott, K. et al. (2016). Does a run/walk strategy decrease cardiac stress during a marathon in non-elite runners? Journal of Science and Medicine in Sport. (Run-walk pacing caused less muscle pain than running straight through, at a similar finish time.)