Ethan BrooksBy Ethan Brooks

Updated November 2026

Training for a first marathon comes down to three things: building a solid aerobic base, progressing your weekly mileage and long run gradually, and giving your body enough recovery to absorb the work. If you follow a structured plan for 16 to 20 weeks, you will be able to cover 26.2 miles on race day without relying on luck or willpower. This guide walks through how to prepare, how to build your schedule, what to do in the final weeks and where beginners most often go wrong.

Step 1: Assess Where You Are Right Now

Before you pick a plan, be honest about your current fitness. A plan designed for someone who runs 35 miles a week will crush a runner who is starting from 10. Most first-time marathoners do best with a base of at least 15 to 20 miles per week for four to six weeks before the plan begins.

Shopping for one? See our guide: Help Me Make Out Training for My First Marathon: 5 Best Guides (2026).

Ask yourself these questions:

  • How many miles am I running per week right now, on average?
  • What is the longest run I have completed in the last month?
  • Have I run consistently for at least three months without injury?
  • How many days per week can I realistically train, including on weekends?

If you can comfortably run 6 to 8 miles in one go and you have been running three or four days a week, you are a reasonable candidate for a standard 18-week plan. If you are starting from zero, add a walk-run phase first. Anyone with a history of injury, heart issues or other health concerns should check with a doctor before starting a marathon program.

Step 2: Choose a Realistic Plan Length and Race Date

Most coaches and published programs run between 16 and 20 weeks. Shorter plans can work for experienced runners, but beginners need time for their bones, tendons and joints to adapt to higher loads. Count backward from your target race date, and give yourself at least one buffer week in case of illness or a missed week of training.

For a deeper look at how structured schedules are put together, see First Time Marathon Training Program: How to Build One That Works. If you are weighing your options, Runner's World First Marathon Training Plan: 7 Best Picks for Beginners (2026) compares several well-known plans side by side.

Step 3: Understand the Core Workouts

A first marathon plan usually includes four types of runs. Each one has a specific job.

Easy Runs

Easy runs should make up the majority of your weekly mileage, often 70 to 80 percent. Keep them at a conversational pace, roughly 60 to 90 seconds per mile slower than your goal marathon pace. If you cannot speak in full sentences, slow down.

Long Runs

The long run is the backbone of marathon training. It builds endurance, teaches your body to burn fat efficiently and gives you practice with fueling and hydration. Beginners typically build the long run from about 8 miles up to 20 miles over the course of the plan, with a peak of 18 to 22 miles about three weeks before race day. Run these at an easy, relaxed pace.

Tempo or Threshold Runs

Tempo runs are sustained efforts at a comfortably hard pace, usually 20 to 40 minutes long. They improve your lactate threshold, which is the pace you can hold before fatigue builds rapidly.

Intervals and Speed Work

Short repeats, such as 4 to 6 times 800 meters at a hard effort with recovery jogs, improve running economy. Beginners should introduce speed work gradually and not every week.

Step 4: Build Your Weekly Schedule

A typical week for a first-time marathoner looks something like this:

Day Workout Type Purpose
Monday Rest or cross-training Recovery
Tuesday Easy run 4 to 6 miles Aerobic base
Wednesday Tempo or intervals 4 to 6 miles total Lactate threshold or speed
Thursday Easy run 3 to 5 miles Recovery pace
Friday Rest or cross-training Recovery
Saturday Easy run 3 to 5 miles Aerobic base
Sunday Long run, building from 8 to 20 miles Endurance

Increase your total weekly mileage by no more than about 10 percent per week. Every three or four weeks, drop the volume by roughly 20 to 30 percent to allow recovery. Those lighter weeks are where adaptation actually happens.

Step 5: Fuel and Hydrate for Long Runs

Your body can store only a limited amount of glycogen, roughly enough for about 90 minutes of hard running. Beyond that, you need to take in carbohydrates. Start practicing fueling on long runs longer than 60 to 75 minutes. Many coaches suggest 30 to 60 grams of carbohydrate per hour, delivered through gels, chews or sports drinks.

Test everything during training. Your stomach needs to tolerate what you will eat on race day. Try different products, timing and quantities on different long runs until you find a combination that works.

Step 6: Taper and Prepare for Race Day

The taper is the final two to three weeks before the race, when you reduce mileage to let your body fully recover while keeping some intensity. A typical taper cuts weekly volume by about 20 to 25 percent in week one, 40 to 50 percent in week two and the final week shrinks to a short shakeout run or two.

Use the taper to rest, sleep well and avoid trying anything new. Plan your race-day logistics, including travel, bib pickup and what you will wear. Run one or two short, easy efforts at goal pace during the final week so your body remembers the rhythm, then stop.

Tips for Your First Marathon Training Block

  1. Log every run. Patterns in fatigue, sleep and soreness show up quickly in a training log.
  2. Prioritize sleep. Most adaptation happens while you rest, so aim for seven to nine hours a night.
  3. Eat enough. Under-fueling leads to fatigue, poor recovery and injury risk.
  4. Strength train two times per week for 20 to 30 minutes, focusing on legs, hips and core.
  5. Replace shoes when they reach roughly 300 to 500 miles, or sooner if the cushioning feels flat.

Common Mistakes Beginners Make

  • Running too fast on easy days. Most beginners run their easy runs too hard, which leaves them too tired for quality workouts.
  • Increasing mileage too quickly. A jump of 20 to 30 percent in one week is a common route to shin splints, stress fractures and tendon pain.
  • Skipping the long run progression. Some runners jump from 10 miles to 20 miles. Build gradually.
  • Ignoring pain. Muscle soreness is normal. Sharp, localized or worsening pain is not. Rest and seek professional advice if pain persists.
  • Trying new gear or food on race day. Anything new should be tested during training.
  • Starting too fast on race day. Begin at a pace that feels almost too easy, especially for the first 10 miles.

Good gear will not make you faster, but it can help you stay comfortable and injury-free through the training block.

  • Brooks Ghost 16 running shoes: A neutral daily trainer with plenty of cushioning, often chosen for high-mileage training weeks. View on Amazon
  • Garmin Forerunner 265 GPS watch: Tracks pace, heart rate and distance so you can keep easy runs easy. View on Amazon
  • Nathan VaporAir hydration vest: Carries water and fuel for long runs without bouncing. View on Amazon
  • Gu Energy Gels: Portable carbohydrate gels for fueling during long runs. View on Amazon

FAQ

How long does it take to train for a first marathon?

Most first-time marathoners train for 16 to 20 weeks, assuming they already run three or four days per week. Starting from zero fitness may require a longer base-building phase before a standard plan begins.

How many miles per week should a beginner run for a marathon?

Peak weekly mileage for first-timers often falls between 25 and 40 miles, depending on the plan and the runner’s body. Consistency matters more than hitting a specific number.

Do I need to run 20 miles before race day?

Most plans include one or two runs of 18 to 22 miles during the build-up. This is enough to prepare you for the distance, and you do not need to run the full 26.2 miles in training.

Can I train for a marathon with only three days a week?

Yes, many plans are built around three to four running days. Make sure at least one of them is a long run, and use cross-training or strength work to support recovery.

Should I walk during a marathon?

Walking through aid stations or using a planned run-walk strategy is a legitimate and effective choice for many first-timers. Practice it during long runs so it feels natural on race day.

What should I do if I miss a week of training?

Do not try to make up the missed mileage. Resume the plan at the week it should be, or repeat a recent week if you missed more than a few days. Adjust your goal if needed.

When should I see a doctor during marathon training?

See a healthcare professional if you experience chest pain, dizziness, unusual shortness of breath, persistent joint pain or swelling, or any symptom that concerns you. This guide is general information and does not replace individual medical advice.

Conclusion

Training for a first marathon is a gradual process of building endurance, respecting recovery and practicing the details that matter on race day. Choose a plan that fits your current fitness, keep most runs easy and increase your load steadily. Trust the process, and you will reach the start line ready to finish.

Ready to choose one?

Ethan Brooks

About Ethan Brooks

Ethan Brooks is part of our editorial team and reviews and edits our marathon & half-marathon guides, checking product details against manufacturer specifications and owner feedback.