How Many 20-Milers Before a Marathon? Real Talk on Distance Training

People love to talk about the “20-miler” like it’s some secret key to marathon training. And, honestly, there’s a reason for that hype. It’s long enough to push your body into the zone where you get tired, hungry, maybe even a little grumpy—right where a lot of your marathon will be spent.

You’ll hear all sorts of opinions, like “You have to get in three 20-milers or you’ll crash and burn.” Truth is, the answer isn’t that cut and dry. The right number depends on things like your running background, injury history, how much time you have to train, and how your body bounces back after big sessions.

• Why the 20-Mile Run Has a Hype
• How Many 20-Milers Make Sense—For Real
• Training Plans: What Coaches Actually Say
• Should You Go Longer or Shorter Instead?
• Tips to Survive (and Nail) Your Long Runs

Why the 20-Mile Run Has a Hype

Ask any group of marathoners about their 20 mile run and you’ll see knowing nods, or maybe a cringe or two. There’s a reason for that reaction: the 20-miler has become a sort of rite of passage because it mirrors what your body and mind go through in the last, toughest stretch of a marathon. Hitting 20 miles in training isn’t random—it’s intentionally close to the wall most runners hit around mile 20 on race day.

When you run a marathon, 20 miles isn’t just a number—it’s the start of the deep fatigue, low glycogen, heavy legs, and mental battles that separate the finishers from the quitters. Logging a 20-miler in training gets your body used to burning through most of its energy stores while teaching your mind you can actually keep going when things get real uncomfortable.

Here’s what’s really happening during a 20 mile run in marathon training:

• Physical readiness: It builds muscle endurance by asking your legs to keep pounding the pavement as they tire, just like you’ll feel late in the race.
• Fueling practice: You get to test your race-day nutrition (gels, chews, sports drinks) and find out what actually sits well after hours of running.
• Mental game: Being on your feet for three hours—or more—gets you used to the boredom, pain, and doubts that hit hard late in a marathon.
• Pacing reality check: You can practice running smart early, so you don’t blow up later on race day.

If you’re curious about how common this is, a survey of U.S. marathon training plans in 2023 found that over 85% included one or more runs of at least 20 miles.

The bottom line? That big 20-miler isn’t about magically making the marathon feel easy. It’s about dialing in your training and mindset for the brutal final stretch, so you’re not shocked when it gets hard. That’s why so many runners swear by it.

How Many 20-Milers Make Sense—For Real

Alright, here’s what runners and coaches actually do. For most folks, banging out a ton of 20 mile run sessions before race day isn’t necessary—or even helpful. In fact, piling on long runs without enough recovery is one of the biggest reasons non-elite runners get injured before a marathon.

If you look at classic marathon training plans, like Hal Higdon’s or Hanson’s, you’ll see most have you doing just one to three 20 mile runs. The sweet spot seems to be around two or three of these long runs in the last six to eight weeks before your race. Why not more? Your body needs serious recovery after a big effort like that.

Super advanced runners, especially those shooting for a time goal, might squeeze in four or five, but that’s rare—and most definitely not for first-timers. For beginners, just completing one or two long runs of this distance is enough to give your legs (and brain) confidence for race day, without breaking down your body. If you’re following most popular marathon training plans, you’ll usually see the longest long run topping out around that 20-mile mark.

• If you’re newer, aim for 1 or maybe 2 twenty milers.
• If you’ve run a marathon before and know you recover well, you can shoot for 2 or 3.
• If you’re running high weekly mileage and going for a time, 3-4 (if healthy and experienced) could work, but more than that usually backfires.

Check this out: A 2022 survey from Strava showed recreational marathoners averaged just two 20 mile runs leading up to their races. And plenty finished strong, so you don’t need a whole stack of them. The key? Quality over quantity—good training beats just grinding out more and more massive runs.

Training Plans: What Coaches Actually Say

If you scroll through marathon training books or chat with coaches, you’ll notice there isn’t just one approach to the 20 mile run. Some classic training plans—think Hal Higdon or Hansons—actually lay things out pretty differently. Higdon’s intermediate plans? You get two or three 20-milers on the schedule before race day, spaced out over the two months before your marathon. But Hansons maxes out their longest run at 16 miles, believing it's more about overall weekly mileage and not smashing your legs with back-to-back monster long runs.

Most modern coaches will tell you it comes down to risk versus reward. A couple of well-timed, high-quality long runs can do the job for most people. Stack up too many and you risk trashing your legs—or worse, getting hurt and missing the starting line. One popular recommendation is to do just two 20 mile run sessions during your peak month before the marathon, usually with at least two weeks in between for recovery.

Here’s what different marathon training plans typically recommend for those long runs:

If you’re working with a coach in person, they’ll likely base the number of long runs on what they see from your workouts, your feedback on soreness, maybe even how crazy your work life is. Flexibility is key—the best plans fit the runner, not just the textbook.

So, don’t worry if your plan isn’t packed with high-mileage heroics. Consistency, smart pacing, and actually listening to your body will take you a lot further than overdoing the long runs just because you saw someone else do it on Strava.

Should You Go Longer or Shorter Instead?

Here’s something a lot of people overthink: Do you really need to hit exactly 20 miles every time, or could you go a bit longer—or even shorter—and still set yourself up for marathon success? The classic 20 mile run became popular mainly because it’s a safe challenge for most people, giving them enough endurance without wrecking the body. But there’s nothing magical about that number. Some training plans top out at 18 miles, while others sneak in a 22-miler.

So, what’s safer or smarter? It depends on your goals and your training history. Shorter long runs (think 16–18 miles) often work for people who build up total weekly mileage or for those who recover slowly after huge runs. Meanwhile, elite marathoners sometimes go longer than 20 miles, but keep in mind, their recovery and nutrition are worlds apart from most runners. For regular folks, going much longer than 20 can spike the risk of injury or plain burnout.

• If it's your first marathon, don't stress if you never cross 20 miles in training. Most bodies adapt just fine as long as the weekly long run is consistent.
• If you’ve run marathons before and want to push your limits, you could try a 21 or 22-miler—but maybe just once, and only if recovery feels fast and easy in your last big build-up.
• Many coaches believe time on your feet matters more than a set number. Running for 3 hours, even if you fall short of 20 miles, can get similar training results for a lot of people.

Check out how some common training plans stack up:

The big takeaway? There’s no single “right” distance. The sweet spot is the farthest distance you can do without needing a week to recover or wrecking the rest of your training. Listen to your body, watch your recovery, and don’t feel like you must copy what your running group does. Smart, sensible buildup will always beat chasing some magic number.

Tips to Survive (and Nail) Your Long Runs

If you’re gearing up for the classic 20 mile run in your marathon training, you want it to count—without falling apart or hating your life. Let’s break it down so you get the most out of the big day and show up stronger at the marathon start line.

• Start Slower Than You Think: Nobody ever brags, “I wish I started that long run faster.” Ease into the first few miles, let your body wake up, and save the hero pace for the last couple miles if you’ve got gas left.
• Fuel Early (and Often): You want to pop your first gel or chew after 45-60 minutes—don’t wait until you’re shaky. Most runners take in 30-60 grams of carbs per hour. Missing fuel is the #1 reason for late-run bonks.
• Stay on Top of Hydration: Even on cooler days, you lose more water than you think. A good rule is 3-7 ounces every 20 minutes. If you sweat salt, add an electrolyte tab or two.
• Don’t Skip the Bathroom Stop: Plan your route so you’re close to a restroom if things get...real. Seriously, it beats hoping for the best when you’re miles from home.
• Break Up the Distance Mentally: Try splitting the run into thirds, or landmark to landmark if you get bored. Reward yourself with a new playlist or snack at mile 15. Trick your brain.
• Practice Like It’s Race Day: Wear the same shoes and gear you’ll use at the marathon. Use the same fuel and hydration too, so no race-day surprises.
• Recovery Starts Right After: You want protein and carbs in the first 30 minutes post-run. Recent sports nutrition studies say a 3:1 carb-to-protein snack (think chocolate milk or a turkey sub) helps repair muscle and refill your tank.

One more thing? Don’t panic if your long run feels hard. Everybody struggles sometimes. Even elite runners have those “why am I doing this” moments. What matters is getting back out there next week.