If you are training for a marathon (26.2 miles!), then you need to run far in your training. So how long should your longest long run be before a marathon?
You would think that is a simple answer—but it’s not! Because running and training for an endurance event such as a marathon can be complicated and intense. No person (or body) is the same.
- An elite marathoner with a history of injury may not run a long run over 20 miles meanwhile a slower runner with a durable body may run up to 24 miles.
- Someone with an estimated marathon finish time of under 3 hours won’t pound the pavement as long as someone with an estimated marathon finish time of 5 hours.
- A newer runner with 6 months to train for a marathon may have more 20+ mile long runs than an experienced runner with only 3 or 4 months, and so forth. You get the picture!
In this article, I am going to help you figure out how far you should run before a marathon.
Specifically, I will cover:
- How far should your longest run be before a marathon?
- What factors determine the length of your long run?
- What’s the longest long run you should do before a marathon?
- What’s the shortest long run you can do before a marathon?
- What is the 30% long run rule?
- When should you do your longest long run in marathon training?
How far to run before a marathon depends on many variables.
But before I get into this, let’s cover some long run basics. The reason you run long in marathon training is to prepare the body and mind for the marathon distance.
A long run triggers changes in the body that allow it to run for a long time such as multiplying mitochondria, increasing capillary density, strengthening tissues and bones, and optimizing energy use—to name a few.
Related: Scientific Benefits of the Long Run
Long runs in marathon training also callous your mind to run far. It takes mental fortitude to keep running especially after those thoughts of quitting pop into your head. Long runs also help you finetune the basics such as what to wear and how to fuel.
Here are some marathon long run basics:
- A long run is considered to be a run that is longer than 90 minutes.
- Unless you have a workout embedded in your long run, you should run your long run at an easy, conversational pace.
- Running with others or listening to podcasts can help you pass the time on your feet and keep it comfortable.
- Do one long run per week. Increase long run duration by no more than 2 miles.
- Long runs peak at about 35 to 40 percent of your weekly volume and build throughout the duration of your marathon training.
- Be sure to fuel before, during, and after your long run. (Read long run fueling tips here).
- Run your longest long run about 3 weeks out from your marathon. (Marathon taper length may vary from 2 weeks to 4 weeks depending on the runner).
*There are exceptions to every one of these rules that I will get to in the article.
So, let’s get to the nuts and bolts on how far to run before a marathon!
How far should your longest run be before a marathon?
On average, how far you run before a marathon aka your peak long run should be 20 miles long: at least 16 miles long and at most 24 miles long. In time, the marathon training longest long run in marathon training will range from 2 hours to 4 hours in length.
This is a wide range for how far to run before a marathon, isn’t it? To understand why there is such a long gap in the duration and distance of a long run, we need to examine the factors that influence how far to run before a marathon.
What factors determine the length of your long run?
There are five main factors that determine how long your longest long run in marathon training will be:
- Training time
- Estimated finish time
- Total weekly volume
- Injury risk
- Running history
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Time to train
How long you have to train for your goal marathon will help determine how long your longest long run in marathon training will be.
If you have ample time to train for a marathon, the longer your long run will be. If you are trying to rush the fitness, you will not be able to run as long. You can’t reverse engineering your training.
By this I mean, you cannot put your peak long run of 20 miles at 3 weeks out from your marathon race and build your long runs backwards in short time frame (unless you are an experience runner running higher volume and long runs already). This could you’re your first long run being 15 miles, for example, starting from single digits. You need to work-up to your peak distance otherwise you risk injury.
I love it when I have athletes who give me a solid six months to build their long runs so that we have multiple 20+ mile long runs in their training block. I have had to have many hard discussions with runners who want to train for a marathon in 12 weeks or less with low volume.
The more 20+ long runs you can do before a marathon, the better chance of a successful marathon race.
Related: How Do You Taper for a Marathon
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Estimated marathon finish time
Your estimated marathon finish time also plays a role in how far you should run before your marathon.
I dive deep into how to determine your estimated marathon finish time here but if you are new to running, your average long run pace is a good indicator of what your marathon pace will be.
Related: How to Predict Your Marathon Time
If you are a more advanced runner, then you can use certain workouts and races of a 10k distance and longer to determine your predicted marathon finish time.
In general, you need to prepare the body for how long you will be on your feet. Therefore, a slower marathon runner may run for longer than a faster marathon runner.
Here are estimated long run durations according to renowned running coach Greg McMillan based on estimated marathon finish times:
- under 3 hours: 1-3 long runs of about 3 hours or your estimated finish time.
- under 4 hours 1-3 long runs of 3:30, (over 20 miles), or no longer than your estimated finish time.
- above 4 hours: long runs of no more than 3:30 hours.
- 5 hours or more: long runs of no more than 4 hours.
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Overall weekly volume
How much you run during the week may also influence how long your longest marathon training run will be. On average, your long run will be around 35-40 percent of your overall weekly volume.
However, there are exceptions to every rule. If you are a low volume runner averaging less than 35 miles per week, your long run may be 45 percent of your overall weekly volume. For runners who will take 5 hours or more to run a marathon will also need more time on their feet during their longest run.
It may seem counterintuitive for runners who run less or run slower to do a longer long run, but they need to prepare their body for being on their feet for longer.
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Injury risk
Running is a high-impact, repetitive sport which puts our bodies at risk for injury. As someone who spent the last three years injured, I can tell you that for a fact!
Someone who tends to be injury-prone will need to be careful of how long their longest long run will be. They will also need to build extra recovery time around their long runs in the form of rest days and cutback weeks (a slight reduction of overall weekly volume).
For example, if you are an injury-prone runner, you may have your long runs every other week with a 12-mile shorter long run interspersed in between.
Related: How I Stopped Being an Injury-Prone Runner
Injury-prone runners need to pay attention to the little things like running easy on their recovery days, proper nutrition, mobility, and SLEEP.
Related: How Much Sleep Do Runners Need?
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Running history
How long you have been running for and how much you have run will impact how long your longest long run will be. If you’ve been running for a long time and/or are used to running higher volume, you will be able to handle longer long runs and more frequent long runs.
If you are new to running, are injury-prone, and are new to long distances, then you will likely need shorter long runs with more recovery.
Related: What to Expect After You Run a Marathon
Should I run 26 miles before marathon?
No, you should not run 26 miles before a marathon. The risks of running the complete marathon distance before the marathon far outweigh any potential benefits.
Running a long run of +/- 20 miles before your marathon will prepare your body and mind for going the distance without compromising your recovery.
Running 26 miles is stressful to the body and can take 4 weeks to recover from. Running 26.2 miles can damage everything from your heart to your tendons, so running that far in your training will put you in a hole that you will not be able to dig yourself out of before race day.
Related: Is it Healthy to Run Back-to-Back Marathons?
Can I run 20 miles 2 weeks before a marathon?
You can run 20 miles 2 weeks before a marathon. However, for most runners, the peak long run should be 3 weeks before a marathon.
Some runners do better with a shorter taper of 10-14 days. However, other runners need more recovery before race day.
Related: Cumulative Fatigue Explained
Figuring out your taper time takes trial and error and involves factors such as volume and how much neuromuscular stimulus you need. If you taper too much, you risk feeling flat on race day. If you taper too little, you risk fatigue.
How much longer should your long run be?
On average, your long run will be about twice the distance of your average daily mileage distance or about 35-40 percent of your total weekly volume.
Remember, there are exceptions to every rule including low mileage runners who will run much farther than their typical daily distance. (See above).
Related: 26 Tips for Going 26.2 Miles
What is the 30% long run rule?
The 30 percent long run rule you have heard is that your long run should not exceed 30 percent of your total weekly volume. Therefore, if you run 50 miles a week, then your long run would not exceed 15 miles.
The 30% rule is a good guide but not really a rule. Running 15 miles as your longest marathon training run will not adequately prepare you for the marathon distance. However, most seasoned runners (unless going for an elite time) do not need to run much more than 50 miles or so a week.
Conversely, if you are a high volume runner, the 30 percent rule could have you running longer than 30 miles in a long run! This is not appropriate for the marathon (but can be for ultra marathons).
What is the longest long run someone will do in marathon training?
The longest marathon training run someone will do in their marathon training will be 24 miles or 4 hours in length. This distance and duration depend on the above 5 factors that influence your longest long run.
What is the shortest long run you can do in marathon training?
The shortest long run someone will do in marathon training is 16 miles or >3 hours in length. Again, this duration is decided by factors such as estimated finish time and overall running volume.
I know people who have only run 14 miles before a marathon. And they finished, but their marathon performance was subpar because they were not properly prepared. They also risked injury.
When should you do your longest long run?
The longest long run in marathon training is usually done about 3 weeks out from your marathon. This timeframe allows you to properly recover from the long run while also absorbing the physiological adaptations that occur from a long run.
Some marathon training plans will have the longest long run just 2 weeks out from a marathon or as much as 4 weeks out from a marathon.
As you think about your long run, remember that your longest long run is not a make or break in your training. Marathon training is about the accumulation of training over the course of several months. No single run or workout determines how your marathon will go!