Marathon Training Plan Calculator
Find out when to start training based on your race date and experience level
Marathon Training Plan Calculator
Find out when to start training based on your race date and experience level
What is a Marathon Training Plan Calculator?
The single most common marathon mistake is starting to train too late. This calculator tells you exactly when to begin, how long each phase lasts, what mileage to target each week, and what your longest training run should be — based on your race date and current experience level.
Marathon training is structured into four phases: base building, development, peak training, and taper. Beginners need 20 weeks to safely build from modest weekly mileage to the 28–32 km long runs required to finish comfortably. Intermediate runners with an existing base need 16 weeks; advanced runners with 70+ km weekly mileage can peak in 12 weeks. Compressing the schedule risks overuse injuries.
The 10% Rule — never increase weekly mileage by more than 10% week-on-week — underpins all three plans. The taper phase (reducing mileage in the final 2 weeks) is equally important: it allows your body to store glycogen, repair micro-damage, and arrive on race day fresh. Skipping the taper is one of the most common mistakes even experienced runners make.
How to Use This Calculator
Peak Weekly Mileage by Level
- • Beginner: 55–60 km/week — build slowly, prioritise completion
- • Intermediate: 75–80 km/week — include tempo and race-pace runs
- • Advanced: 100–110 km/week — double days and back-to-back long runs
Why Marathon Training Timelines Aren't Just About Mileage
The marathon punishes under-preparation more severely than shorter races because of glycogen depletion — the body typically stores enough glycogen for roughly 30-32km of running, which is exactly why "the wall" is such a well-known phenomenon specifically at that point in the race, and why the long training runs in these plans exist to teach the body to spare glycogen and burn fat more efficiently at race pace.
The taper is often the psychologically hardest part of marathon training precisely because it feels counterintuitive — reducing volume right when race day approaches triggers real anxiety in many runners ("taper anxiety" is a genuinely common, well-documented experience) even though the physiological benefit of arriving fresh is well established and consistently outperforms continuing to train hard into race week.
Because marathon plans run 12-20 weeks, life-schedule realism matters more here than for shorter training blocks — illness, work travel, and minor niggles are near-certain to happen somewhere across that span, which is why experienced coaches build in buffer weeks and flexible scheduling rather than treating any single missed session as plan-ending.
?Frequently Asked Questions
Beginners should start 20 weeks out, intermediate runners 16 weeks, and advanced runners 12 weeks. These durations assume you are already running regularly (at least 3 days per week). If you are coming from no running base, add 8–12 additional weeks of foundational running before starting the structured plan.
Most training plans cap the long run at 32–38 km (20–24 miles), done 2–3 weeks before the race. Running the full 42.195 km in training is unnecessary and increases injury risk. Your body will complete the final kilometres on race day using training adaptation, glycogen stores from taper, and race-day adrenaline.
If you have fewer than 12 weeks, completing a full structured plan is not feasible. You can still run the marathon — but treat it as a training run rather than a race, run conservatively, and plan to walk sections. Use this experience to choose a target marathon 20+ weeks away and follow a proper plan from the start.
No. All three plans include rest days and easy recovery days. Running every day without rest is a common cause of overuse injuries like shin splints, IT band syndrome, and stress fractures. Most plans run 4–5 days per week. Cross-training (cycling, swimming) on rest days maintains fitness without the impact load of running.
The wall is the sharp drop in performance runners experience around 30-32km into a marathon, caused primarily by depleting the body's stored glycogen, which forces a switch to slower, less efficient fat metabolism. Long training runs, particularly those extending to 28-32km, teach the body to become more efficient at using fat for fuel and spare glycogen for longer at a given pace, which is the main physiological reason the long run is treated as the most important session in every marathon plan.
"Taper anxiety" — restlessness, doubt, and sometimes feeling unusually heavy-legged during reduced training — is a well-documented and common experience, often because runners misinterpret normal fatigue clearing (which can temporarily feel odd) as a sign of losing fitness. Trusting the taper is difficult psychologically precisely because it contradicts the instinct to keep training hard, even though the physiological evidence for reduced volume before a race is consistently strong.
Yes, and it should be expected rather than treated as plan failure. Across a training block this long, illness, work travel, and minor injuries are near-certain to interrupt training at some point for most people. Missing a week or two, then resuming roughly where you left off (rather than trying to make up lost volume all at once), rarely derails an otherwise consistent training block — the cumulative effect of the weeks you did complete matters more than a perfect, uninterrupted record.