Marathon training for beginners: what 16 to 20 weeks looks like
By the Kiki team · Updated · 7 min read
Beginners usually train for a marathon (26.2 miles or 42.2 km) over 16 to 20 weeks. Build a base first, run mostly easy, and grow one weekly long run to about 18 to 20 miles (29 to 32 km) roughly three weeks before race day. Practice fueling on long runs, then taper for two to three weeks.
Are you ready to start?
A beginner marathon plan works best if you're already running about 15 to 20 miles (25 to 30 km) a week and can run 6 miles (10 km) comfortably. Many coaches suggest running a half marathon first. If you're not there yet, spend a couple of months building a base before you start the plan.
The shape of a marathon plan
| Phase | Roughly | What it's for |
|---|---|---|
| Base | Weeks 1–5 | Consistent easy running, a long run that grows slowly. |
| Build | Weeks 6–11 | More distance, longer long runs, some steady or faster running. |
| Peak | Weeks 12–15 | Your biggest weeks and longest runs, up to 18–20 miles. |
| Taper | Last 2–3 weeks | Less running so you arrive fresh. |
The long run
The long run is the heart of marathon training. Run it slowly, at a pace where you could chat, and take walk breaks if they help. It builds endurance and gives you a dress rehearsal for race day: the same breakfast, shoes, kit and fueling.
Keep most running easy
Research on endurance athletes, notably by sports scientist Stephen Seiler, found that they do roughly 80% of their training at a low intensity. Easy running builds your aerobic engine with less wear and tear, which matters most in a long marathon build.
Fueling
Your body can only store enough carbohydrate for a couple of hours of hard running. Sports nutrition guidance commonly suggests about 30 to 60 grams of carbohydrate per hour for longer events, from gels, chews or sports drink. Practice on every long run so your stomach is used to it.
Tapering
Cut your running back for the final two to three weeks while keeping a few short, faster efforts. Sleep well and eat normally. It's common to feel sluggish during the taper; trust it.
Race-day pacing
- Start slower than your goal pace. The first miles should feel easy.
- Fuel early and often, before you feel you need it.
- Walk through water stations if it helps you drink.
- Save your effort for the last 10K. That's where the race really begins.
Coach's tip: Life will interrupt your training. A missed week or a cold won't ruin your marathon. What matters is adjusting sensibly instead of cramming. Kiki rebalances your upcoming weeks when that happens.
Common questions
- How long does it take a beginner to train for a marathon?
- Usually 16 to 20 weeks, assuming you can already run about 6 miles (10 km) comfortably. Newer runners should build a base first.
- Do I need to run 26.2 miles before the marathon?
- No. Most plans peak at 18 to 20 miles (29 to 32 km). The taper and race-day atmosphere carry you the rest of the way.
- Can I walk during a marathon?
- Yes. Many first-time marathoners use planned walk breaks, and plenty finish faster that way than by running until they're forced to walk.
This guide is general information, not medical advice. If you have pain, an injury or a health condition, talk to a qualified professional.