How to Train for a Marathon: The Complete Guide

Me finishing my first marathon at Wineglass in 2011

Marathon training typically takes 16-20 weeks, built on mostly easy running, progressive long runs, and a fueling strategy you practice before race day. It's also important to have a solid base of endurance training under you before starting your marathon build. This guide is for first timers, experienced runners, and everyone in between who wants to train smarter and cover all their bases for their marathon build. I am a USATF and RRCA certified running coach of over 8 years, and I've coached hundreds of runners to PRs and even Olympic Trials qualifiers. This is an evidence-based guide to training for your marathon so you can show up on race day feeling ready and believing in yourself.

So you want to run a marathon? Whether it's your first or your 10th, I want to walk you through everything you should practice in training and how to show up to race day prepared.

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Key Takeaways

• Marathon training takes 16-20 weeks, and it works best on top of an established base of 15-20 miles per week

• 80% of your running should be easy. Speed work sharpens your fitness, it doesn't build it

• You do not need a 20 miler. A 16-18 mile long run followed the next day by an 8-10 miler gets the job done

• Fueling is a skill you practice on every long run: 40-90g of carbs, 6-12 oz of fluid, and 200-600mg of sodium per hour

• Trust the taper, stay disciplined in the first 10k, and give yourself 4-6 weeks of reverse taper after the race

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1. Before You Start: Are You Ready to Train for a Marathon?

Before you start any marathon build, make sure you have some consistency under you: at least 3-6 months of regular running, comfortably handling 15-20 miles per week. You can obviously start lower, but this guide is setting you up so that when you start, you're on solid ground and not trying to catch up during your marathon block. Also make sure you really, truly want to run a marathon and it's not just running culture pushing you toward one. As someone who has been running for over 30 years, I love all the race distances, so don't sleep on a 10k or half marathon if that's where your heart is.

For a new or returning runner, give yourself some time to get back. Maybe you ran a marathon a few years ago, and that does give you some experience, but it's still important to spend a few months (or more) establishing consistency and building back to double digit long runs. While it's not a must to currently be running double digit long runs, it's a really good starting point for the road ahead.

If you haven't chosen your race yet, choose one that meets your criteria. Take into consideration the usual weather conditions on race day, the course itself, and its timing in your life. Some runners really struggle with early fall marathons because they struggle to get out in the summer, while other runners find winter training too hard for them. Consider your life and any stressors to set up your race to be the best case scenario for your success.

2. How Long Does Marathon Training Take?

The average marathon build is 16-20 weeks of specific marathon-related training, but that assumes you're coming into your marathon with an established base. As mentioned earlier, if you're coming in with zero mileage or off an injury or break, give yourself a few months first and then jump into your marathon build. We call this the base building period. It won't be specific to the marathon, but it prepares you for it.

The reason I don't usually recommend longer than 16-20 weeks is because this is the most time you need in your specific phase of marathon training. Anything beyond this is really just base building, which is better done outside your marathon block. A sample marathon block consists of a little bit of base training in the beginning, then a build phase where we really focus in on marathon-specific training. We hit our peak, where the biggest training is set to really light the fire of your fitness, and then we taper to race day.

3. What Are the Core Principles of Marathon Training?

Marathon training is built on four principles: mostly easy running, progressive overload, race-day specificity, and consistency. Easy running is your engine here, and it builds your aerobic base. Think of the 80/20 rule, where 80% of training is easy and 20% is more intense. This isn't just coaching folklore: exercise physiologist Stephen Seiler's research on elite endurance athletes across running, cycling, and cross-country skiing consistently found that the best performers in the world spend roughly 80% of their training at low intensity(read more about it here ).You also want polarized intensity distribution between your training runs so it's not everything at the same pace every day. A well designed build is progressive overload without the injury tax.

One of the big things you notice about a marathon training block is the specificity in it and how the plan changes as you go. You may notice long runs building up in distance and marathon pace blocks getting longer until they peak. As you taper, you'll start getting shorter workouts done at faster speeds and your long run distance decreasing. This specificity is built in for the exact reason you might think: it's getting you ready to feel your best on race day. As you go through your build, remember one principle and carry it with you: consistency beats heroics every time.

4. What Should a Marathon Training Week Look Like?

A typical training week should include some easy runs, some strides, a speed session, and a long run that usually includes some pace work built into it, all of this to support the periodization required to have your best race.

One of the most common questions asked regarding marathons is "do I need to run a 20 miler?" and my answer is always the same. You can get a similar fatigue by doing a 16-18 miler followed the next day by an 8-10 miler. Sometimes a 20 miler is too much time on your feet or just intimidating, and if that's the case, follow up your 16-18 miler with a moderate long run on tired legs and you'll find that can support you just as well. If you aren't going to run a 20 miler, just make sure your build includes plenty of 16 and 18 mile long runs.

Keep your easy days easy. We really mean it. Whatever your test is, whether it's RPE, the talk test, or HR data from a chest strap, keep those days easy, because with a structured week like the one above, you want easy days to keep you fresher for your harder days.

When thinking of marathon pace, acknowledge that early on, goal marathon pace might feel really hard. It's OK to start at your current PR marathon pace (or slower) at the beginning of a build and work your way up. We want this pace to feel manageable on race day. You'll tend to find after doing a lot of marathon pace work in the beginning to middle of your build that faster speeds feel easier at the end of the training block. Make sure you don't overdo it with your speed workouts. They're for sharpening your fitness, not trying to set a 5k PR.

Make sure on your rest days you really focus on recovering. As this build goes on, you'll find fatigue creeping up more and more, and your rest days are part of the answer to the question "how will I be able to keep this up?" The other answer is down weeks, which are a must with all of my athletes. Down weeks allow intensity and volume to come down a little bit so your body has a chance to absorb all that stress and recover for the next big block. Don't make the mistake of thinking your runs will feel easier during a down week. Usually it's quite the opposite, because the goal of the down week is to feel good for the upcoming weeks.

Here is a sample week for a beginner and an intermediate runner:

	Mon	Tues	Wed	Thurs	Fri	Sat	Sun
Beginner	Rest	4 miles w/ strides	3 x 8 min at threshold, 3 min jog recovery	Rest	4 miles	14 miles	6 miles w/ strides
Intermediate	Rest	5 miles w/ strides	3 x 1.5 miles at MP, 3 min jog recovery	Rest	5 miles	16 miles	8 miles w/ strides

5. Strength Training for Marathon Runners

It's important to focus first and foremost on the running part of your marathon training block, but if you have the time, don't forget to add in strength training, because it can have very important benefits for your race. In addition to helping you gain power, one of the best things strength training does for runners is improve your running economy, helping you run longer while keeping the same form, which helps you maintain your pace.

A good amount of strength training is 2 days a week during your marathon training block. Make sure not to schedule these the day before your long run or speed workout. If you need help planning your strength training workouts, look no further than our Strength Training Plans, designed specifically for your race training block and complete with videos on how to do each lift.

6. Fueling Your Training (and Race Day)

One of the most important things to get right in your marathon build is your fueling. Carb loading before long runs and races, breakfast before long runs, intra-run fueling, water, and hydration all become a big part of what you practice in training. Long runs become training grounds for you to learn what works and what doesn't for you, so it's important to try different gels and electrolyte powders in training.

A good number of carbs to shoot for per hour is 40-60g on the lower end and 60-90g on the higher end. These ranges line up with the International Society of Sports Nutrition's position on endurance fueling, which recommends carbohydrate intake during efforts over 2 hours, with the higher intakes (up to 90g per hour) relying on mixed carb sources like glucose plus fructose that your gut can actually absorb(read more about it here). When it comes to hydration, most runners on average need 6 to 12 ounces of fluid and 200 to 600 milligrams of sodium per hour.

There are so many different products available to help you hit these numbers today. Most gels now contain sodium, and drink mixes range from high-sodium electrolyte powders you can add to your water to lower-sodium options that come with more carbs. One of the best things you can do when you start training for a marathon is track which gels, electrolyte powders, and other products work best for you. Come up with a fueling plan that helps you reach these averages, and then you can determine if that's enough, as some runners require even more than these numbers.

Check out our Fueling and Hydration guide, which breaks down a lot of this information for you here.

7. Pacing: How to Pick a Realistic Marathon Goal

So you want to pick a realistic goal for your first marathon, and you want to just use a calculator and call it a day? Not so fast. One of the most important things to realize is that a lot of calculators don't do a good job of estimating a realistic marathon pace for your first marathon. Sometimes runners input results from a 5k, which throws off the calculator and isn't a good estimating distance. Other times, the calculator assumes runners have the experience to extend from their half marathon to the marathon distance, even though they've never run that far before. A lot of what happens in a marathon happens from mile 20 on, and so much of that is learned experience from having done this before.

One of the best ways for new runners to run a marathon is by negative splitting it. A common technique is the 10/10/10 method. In this pacing method, you run the first 10 miles 5-10 seconds per mile slower than goal marathon pace, the next 10 at marathon pace, and the last 10k slightly faster than marathon pace. This technique is great for first timers because it helps you avoid crashing and burning, and it gives you the best chance to have your best day. As you get more experienced, this technique might become a bit more limiting.

Me at my 7th Marathon at the California International Marathon, my current PR!

The last thing to note about marathon pace: it shouldn't feel all out or impossible to hold in training. Early in the training block you might have to ease into it, but as you get closer to race day, you should be able to run blocks of this pace without feeling like you're barely hanging on. If you are, it's best to slow down to a more maintainable pace in training for that run.

8. Injury Prevention and What to Do When Something Hurts

Injuries are a part of every runner's journey. It's not if you'll get injured, it's when in your career the injury will come. Don't always look at them as something you did wrong. Sometimes when chasing something you've never done before, something can pop up. That said, there are ways to keep your body healthy and protected during your marathon build, and injuries to look out for.

The most common injuries for marathon runners tend to be overuse injuries like runner's knee, iliotibial band syndrome, shin splints, Achilles tendinopathy, and plantar fasciitis. These injuries are usually caused by ramping up your mileage too quickly and ignoring rest days. It's important to recognize the warning signs and know how to proceed. Some good starting questions:

• Does it wake you up in the middle of the night because of pain?

• Does the pain get worse as the run goes on?

• Does the pain occur when you're not exercising, or only after exercising?

  
  

These are good starting points, and adding an extra rest day or two can help you see what's going on. If there's no change, it's time to see a physical therapist and get evaluated, because the quicker you can diagnose the injury and start exercises to heal it, the better off you'll be. Some injuries want you to keep loading the area, just with fewer miles, while other injuries require full rest.

With any marathon build, it's important to have a really solid plan that keeps you from doing too much too soon. If you're looking for a science backed plan to help you prepare for your marathon, look no further than our Marathon Training Plans. Most importantly, don't forget the boring stuff like managing stress in your life and getting enough sleep each night, as these are the things that help your body handle everything that comes with the marathon.

9. Why Do You Taper Before a Marathon?

The taper is the 2-3 week reduction in training volume before your marathon that lets your body absorb fitness and arrive at the start line fresh. The taper is one of the most important parts of your marathon build. It's when your body has a chance to eliminate cumulative fatigue, repair muscle micro-tears, fully restore glycogen, and bring your central nervous system back to peak sharpness. The research backs this up: a meta-analysis of taper studies found that a roughly 2 week taper cutting training volume by 40-60% (while keeping intensity) improved race performance by around 2-3%, which at marathon pace is minutes, not seconds(read more about it here). All those weeks of grinding? The taper is what allows it all to come together so your body can be at its absolute best on race day. The taper is what allows you to go further and faster than you're able to go in training. During training, your body is constantly in a state of cumulative fatigue because it's building for race day. The taper prepares your body for the task of the marathon, and it's why you don't need to run 26.2 miles before race day.

The most important thing you can do during the taper is not fall into the common traps. Your workouts or long runs are not going to instantly feel easier. In fact, they might feel a little harder the first week of the taper because your body is starting to recover and is now in a different state than it was during the previous training weeks. Don't assume your fitness is gone, and don't start judging your fitness if a workout doesn't feel easier. Most plans lean on sharpening workouts during the taper: shorter sessions focused on speed or paces faster than marathon pace. Those workouts might feel harder, but they're done for a reason: to prepare you for race day. Also, be careful not to let phantom pains that pop up during the taper make you question whether your body is healthy. Monitor any pains that come up, but know that phantom pains are absolutely a part of every taper. At the end of the day, the point of the taper is for you to feel your absolute best on race day and not a day sooner.

10. Race Week and Race Day Execution

The way you execute race week can have a huge impact on how you perform on race day, so let's talk about the things that matter most. Carb loading is what you'll hear about the most during race week, but if you practiced carb loading before every long run during your training block, at this point it's second nature. You'll just want to do a little more of it. There are great calculators all over the internet to help you dial in the numbers, but this is one of those things where practicing throughout your training block makes race week much easier to execute.

The other thing you want to figure out during race week is logistics. Make sure you know the race start time, where it starts, what gear you're wearing (again, practice with your race day gear in training), whether you'll need throw-away clothes, when to enter corrals, where the aid stations are, and so on. One of the things that can help you the most on race week is our Race Day Planner. Fill it out so you have everything with you on race day. Find the planner here. You can also grab our Race Week Mindset Checklist here and pair the two together.

As far as race day execution, have discipline in your first 10k. It can be very easy to get carried away at the beginning of the race. The pace might only feel like a 2-4 on the RPE scale, and that's OK. You're trained to run 26.2 miles, so the first few are just getting your feet under you. The only thing you can do in those miles is waste energy and set yourself back later on.

The other big key part of the race is the middle miles, from 13.1 to 19. This is when you hit halfway, and again, you can feel like the finish is close and start picking it up a little. This is where you need to stick to the plan. If you're following the 10/10/10 method, this is where you run race pace and not faster. Do not dig too deep here, because that's one of the biggest causes of hitting the wall hard at miles 20 and 21.

Also make sure you're fueling early and often. The marathon isn't built for making up poor early fueling later in the race. You're fighting a deficit, and you can't catch up as the race goes on. Don't skip any early gels or push any back from the fueling plan you created earlier. Following your plan saves you from having your body run out of fuel when it needs it most during the last 10k. It's also highly advisable to fuel by time instead of distance. You might have bathroom breaks or other things happen during a race that stop your forward progress, but time keeps on ticking. Fuel your body on schedule instead of adding time between gels because you were stopped for any reason.

11. After the Marathon: Recovery and What's Next

So you completed your marathon. Congrats! Now it's on to the toughest thing: your recovery and reverse taper, and not rushing back into things. The momentum from this build, whatever your result, is going to carry forward, and the most important thing you can do for yourself is first and foremost rest. Take 1-2 weeks minimum of complete rest. There's no need to rush back out there. We aren't trying to hold on to our fitness forever. We ran our race and used our fitness, and now it's time to deload and destress before the next race.

Then, as you come back, it's time to work on the reverse taper: slowly adding days and miles back to where you were before, but being very careful. For example, for a runner doing 5 days of running a week, their first week back I would have them run only 3 times, all easy runs. Week by week, slowly add back miles, and then at the very end you can add back intensity. This reverse taper should take 4-6 weeks, and intensity (like workouts or strides) should definitely wait until the very end of this period. Not only do you want to give your body time to really recover, you want to see if there are any trouble spots post race that you need to address before building for your next race. Pay very close attention to anything that doesn't feel right, and don't ignore it before adding too much back in.

When choosing when to race again, everyone is a little different, but with 4-6 weeks of reverse taper plus some completely off time post race, and a marathon build being 4-6 months long, I would give yourself 6-8 months before your next marathon. If you're more seasoned, it can be 4-6 months, but if this was your first, do not immediately hop back in. Give yourself time to recover, work on some shorter distance stuff as you rebuild your endurance and fitness, and then you can really get into that next marathon build. Most importantly, don't fear losing fitness. The goal of a successful training block is to peak for race day, take a deposit of fitness from your training bank, and then when you start your next build, you'll be starting at a higher fitness level than you did for this one. That allows you to continually push your floor up and your ceiling even higher.

Frequently Asked Questions

How many miles a week do I need to run to train for a marathon?

Before starting a marathon build, you should be comfortably running 15-20 miles per week with at least 3-6 months of consistency behind you. During the build itself, your weekly mileage will grow progressively from there, with long runs building toward 16-18 miles or more. The exact peak depends on your experience level, but consistency at a sustainable volume beats heroic weeks every time.

Can I train for a marathon in 12 weeks?

The ideal marathon build is 16-20 weeks of marathon-specific training on top of an established base. A 12-week build can work for an experienced runner already carrying solid mileage, but for most runners it compresses the build phase and increases injury risk. If you have less than 16 weeks, spend what time you have wisely and adjust your goal, or consider targeting a later race so you can train properly.

Do I need to run 20 miles before a marathon?

No. You can get similar fatigue and fitness benefits from a 16-18 miler followed the next day by an 8-10 mile moderate run on tired legs. If a 20 miler is too much time on your feet or feels intimidating, back-to-back long runs are a great substitute. Just make sure your build includes plenty of 16 and 18 mile long runs. The taper is what allows you to cover 26.2 on race day without ever running it in training.

How slow should my easy runs be?

Easy means genuinely easy, whether you measure it by RPE, the talk test, or heart rate data from a chest strap. You should be able to hold a conversation. Easy days exist to keep you fresh for your harder days, so if you're not sure whether a run is easy enough, slow down. Your speed sessions and long runs are where fitness gets sharpened, and they only work if your easy days let you recover.

What should I eat during a marathon?

Aim for 40-60g of carbs per hour on the lower end and 60-90g on the higher end, along with 6 to 12 ounces of fluid and 200 to 600 milligrams of sodium per hour. Practice this exact plan during your long runs so nothing is new on race day, fuel early and often (you cannot make up a deficit late in the race), and fuel by time rather than distance so bathroom breaks or slowdowns don't throw off your schedule.

Conclusion

I hope this guide was helpful. I wanted to cover all the things I wish I knew before my first marathon and put them in one post for you to read through. This guide can help you remember everything when you start your training block and not be caught off guard mid-build by something you weren't thinking of. So much goes into a successful marathon training block, and the more you practice everything, the more prepared you'll feel on race day. If you're looking for assistance with your next marathon training block, look no further than our Marathon Training Plans. They include tons of information to prepare you, a plan to support you at any level, and a recovery plan for post race so you can recover properly. These plans are perfect for your next marathon and will help take some of the most important parts of your marathon training off your plate.

Nick Klastava is the CEO of all things Running Explained and has been a runner for 30 years. A USATF and RRCA certified running coach for 8 years, he has coached everyone from runners breaking 5 hours in the marathon, to first-time Boston qualifiers, to athletes racing the US Olympic Marathon Trials. He loves helping runners chase their potential and break through the limiting mindsets that hold most of them back. He holds PRs of 1:10 in the half marathon (2018) and 2:30 in the marathon (2019).