Half Marathon Training Plan How to Choose the Right One

Most half marathon training plans run 12-16 weeks, and the right length depends entirely on your current base. If you're already running 15+ miles a week comfortably, 10-12 weeks is enough. Between 10 and 15 miles a week, use the full 16 weeks. Under 10 miles a week, spend 3-4 weeks base-building before you start a plan at all. Below: a diagnostic for which plan tier fits you, the readiness check before week one, how to calculate your own training paces, week-by-week mileage for all three tiers, what to do if you miss a week or get sick, and the strength work most plans skip.

Pick the wrong tier and the plan doesn't just feel harder — it starts breaking you down before it builds you up, usually by week three or four when the mileage jumps outrun what your legs can absorb. The fix isn't a better plan; it's matching the one you already have to where you're actually starting from, which is exactly what the sections below help you do.

Which Half Marathon Plan Fits You? A Diagnostic

Every ranking plan page hands you a generic 12-week template and hopes it fits. It usually doesn't. The trick is matching the plan to where you actually are right now — not where you'd like to be.

Use the table below with three numbers: your current weekly mileage, your longest run in the last 4 weeks, and how many weeks you have until race day.

One rule overrides all of this: if you have fewer than 12 weeks to race day and under 10 miles a week of base, don't start a half marathon plan yet. Run a base-building block first. Starting the Novice plan's week one long run on a base that isn't there is exactly how niggles turn into injuries by week four.

Readiness Benchmark: Are You Ready to Start Week 1?

Here's a pattern I see repeatedly with new athletes: most runners who stall in weeks 1-2 of a half marathon plan weren't undertrained on mileage. They skipped the base-building phase entirely and jumped straight into the plan's first interval session, legs and tendons unprepared for that kind of load.

Before you open a plan's week one, check you can do this: run 4 miles (6.4km) continuously without stopping, and hold a weekly mileage base of 10-15 miles for 3 consecutive weeks. If you can tick both boxes, start on day one with confidence.

If you can't yet, that's fine — that's correct, even, for where you are. Spend 3-4 weeks on a simple base-building mini-structure first: 3 runs a week, adding roughly 1 mile a week, all at an easy, conversational pace. Then come back and start the plan properly.

How to Calculate Your Training Paces

Every ranking plan tells you "run easy" or "run tempo" without ever explaining how to work out what that means for you personally. Here are the pace bands I use with athletes across every experience tier, derived from one number: your most recent 10K time.

Work from a race result that's genuinely recent — a 10K time from eighteen months ago tells you nothing useful about your fitness today. A full calculator with more race-distance inputs lives on our dedicated pace calculator page; this section gives you the method behind it.

Your Week-by-Week Structure

Every plan tier below is built on the same three non-negotiable weekly sessions: a long run, one quality or speed session, and easy running to fill the rest of the week. Layer on top of that the 10% rule — don't increase total weekly mileage by more than 10% from one week to the next — and you have the whole framework.

Novice Plan (16 weeks)

Intermediate Plan (12-14 weeks)

Advanced Plan (10-12 weeks)

Whichever tier you're in, the full detail on how the long run itself should progress — distance, pace, and terrain choices — lives on our long run progression page. And once you're mid-plan, how to pace your long runs and race day is worth reading well before you get there.

What to Do If You Miss a Week or Get Sick Mid-Plan

This happens to almost everyone at some point in a 12-16 week block, and no ranking page tells you what to actually do about it. Here's the rule-based approach I use with my own athletes.

Missed 1-3 days — resume as normal, nothing to fix. Missed 4-7 days through illness or travel — drop back one full week in the schedule rather than trying to cram the lost mileage back in. Missed 2+ weeks — reassess your goal properly: either drop one plan tier, or extend the base-building phase, and if you're under 4 weeks from race day, seriously consider deferring.

One of my athletes picked up a chest infection in week 9 of a 14-week block. Rather than cramming the missed mileage back in, I dropped her back to week 7's schedule. She still ran a personal best on race day. The mileage you panic about losing is rarely the mileage that costs you the race.

As a general return-to-run threshold after illness: wait until you've been fever-free for 24-48 hours before you lace back up. For the fuller version of this, including travel and irregular work schedules, see your original training plan recovery guidance.

Strength Training and Injury Prevention

I keep this section short deliberately, because the full routine deserves its own page. Twice a week, on non-running days, do simple strength work focused on your hips, glutes, and core — this is what keeps your form together when your legs are tired late in a long run, and it's the single most under-used tool for injury prevention I see among the runners I coach.

For the complete routine, sets, and reps, see a full strength routine built specifically for half marathon runners.

Frequently Asked Questions

How long should a half marathon training plan be?

Most plans run 12-16 weeks. If you're already running 15+ miles a week comfortably, 10-12 weeks is enough. Between 10 and 15 miles a week, use the full 16 weeks. Under 10 miles a week, spend 3-4 weeks base-building first.

What's the minimum weekly mileage before starting?

I want to see 10-15 miles a week held for 3 consecutive weeks, plus a continuous 4-mile (6.4km) run under your belt. Below that, you're not ready for week one yet — spend a few weeks base-building instead.

Can I train running only 3-4 days a week?

Yes, plenty of my athletes finish strong on three runs a week. It takes a different structure to the standard 5-day plan, though — see our dedicated three-runs-a-week page for the full schedule.

How much should weekly mileage increase week to week?

No more than 10% a week, as a general ceiling. Push much harder than that regularly and niggles start turning into injuries.

Do I need speed workouts, or is easy running enough?

For finishing, easy running and one long run a week will get you there. For running faster than your last half, you need at least one quality session — tempo or intervals — most weeks.

What pace should my long runs be?

Roughly 90 seconds to 2 minutes per mile slower than your recent 10K pace. It should feel conversational, not laboured — if you can't hold a sentence, you're going too fast.

Is a run-walk method okay for a half marathon?

Absolutely — it's a legitimate strategy, not a compromise, and I've coached plenty of confident finishers using it. Read our full run-walk method guide for how to structure the intervals properly.

How many rest days do I need each week?

At least one full rest day, and most beginners do better with two. Rest days are where the training actually gets absorbed — they're not wasted time.

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