HOW LONG TO TRAIN FOR A MARATHON?

"I want to run a marathon — how long do I need to prepare?" The runningsociety coaching team hears this regularly — and the answer depends less on the calendar than on what you already bring to the table. Head Coach and Founder Florian Gast has guided athletes from 3:15h to 5:30h through their first marathons — and the preparation was different every time, but one thing was always the same: those who give themselves too little time regret it by kilometre 35.

The honest answer: 16–20 weeks for most

The most common recommendation is 16–20 weeks for runners without marathon experience. That sounds like a lot, but the timeframe makes sense for a concrete reason: your body needs time to adapt to increasing loads — not just the muscles, but above all the tendons, ligaments, and bones, which adapt more slowly than cardiovascular fitness.

Starting a 12-week plan without a solid running base beforehand doesn't just risk a slow time — it risks an injury before you even reach the start line.

As a rule of thumb: - Less than 6 months of regular running → run a half marathon first, then a marathon - 6–12 months of base training, long run up to 15 km → 20-week marathon plan - Already completed 10k races, long runs up to 18 km → 16 weeks is enough

What you should have before starting a plan

Most training plans — including those on TrainingPeaks — assume a base level of fitness. Specifically:

Why this matters: a 20-week marathon plan doesn't start from zero. It opens in week one with several medium-length runs. If you're not prepared for that, you fall behind immediately — and end up doing too much training too fast, which is the most common cause of overuse injuries.

What solid marathon preparation looks like

The training structure over 16–20 weeks:

Good marathon preparation has four core elements:

1. Long run (once a week) The most important run of the week. Starting at 90–120 minutes, building up to 30–35 km at peak (3–4 weeks before the race). Always slow — 60–90 seconds per kilometre slower than goal marathon pace.

2. Medium-long run (once a week) 60–90 minutes at a comfortable pace. Builds your base and fatigue resistance.

3. Quality session (once a week) Depending on your goal: threshold-pace tempo run, marathon-race-pace intervals, or progression runs. This is the session that makes goal times achievable.

4. Easy runs (the rest) Everything else is easy. Really easy. This is where most people go wrong.

The most common mistakes in preparation

Too much too soon: the "10 percent rule" is a useful guideline — never increase weekly running volume by more than 10% per week. Jumping from 30 to 60 km in three weeks gets paid back in injuries.

Running recovery runs too fast: easy runs get run too fast — the most common mistake. The result: chronic fatigue, stagnating performance, higher injury risk.

Ignoring the taper: volume drops significantly in the final 2–3 weeks before the marathon. Many runners get nervous and train too much. That destroys the supercompensation you built up over 16 weeks.

Running the long run too fast: the long run isn't a race. It's a training stimulus for your energy system and your tendons. Run it too fast and you won't enter the next week recovered.

Nutrition and recovery: the underrated half

Many people focus exclusively on the running sessions and forget that the body adapts outside of training. Sleep, nutrition, and active recovery aren't bonus features — they're part of the training plan.

Important for marathon runners: carbohydrate training (long runs without prior carb intake train fat metabolism) and testing gels/race-day fueling in advance — never try something for the first time on race day.

What is a realistic first marathon time?

That depends on your 10k time. As a rough guide: - 10k in 55 min → marathon approx. 4:20–4:40 h - 10k in 50 min → marathon approx. 3:55–4:10 h - 10k in 45 min → marathon approx. 3:30–3:45 h

For your first marathon, the rule is: finishing is the goal. Runners who go after a target time in their second marathon perform noticeably better — because they already know what kilometer 35 feels like.

Conclusion: plan enough time

A marathon isn't a spontaneous decision — and that's a good thing. 16–20 weeks of consistent training transform your body in ways you'll feel in everyday life: more energy, a better mood, a completely new sense of your own body.

The photo shows Florian talking with Imke Salander — an athlete with a track and field background and a passionate marathon runner whom Florian coaches for HYROX. She loves marathons: by day and by night.

Want to get a feel for the community first? Come to one of our runningsociety runs in Munich — no commitment, no plan needed.

If you're more ambitious and chasing a real goal time: runningsociety offers structured marathon programs for every level — from "first time crossing the finish line" to "sub-3:30". We work with top coach Benz Franke among others. Together we build a plan that fits your life and your starting point. Book a free intro call.

June 4, 2026