How Far Should You Run Before a Half Marathon?

How far should you run before a half marathon?

The half marathon is one of the most popular distances for runners of all experience levels and abilities. Some runners have the goal of finishing, while others want to earn a PR. Depending on your experience and goals, training for a half marathon will vary. How many miles you run per week, how many days per week you run, and how far you run before a half marathon all are dependent on current fitness and background.

This article will help you determine how far you should run before a half marathon. This article first looks at common training practices and what current research says, before offering guidelines. At the end, you will find suggestions on how to extend your long run distance in half marathon training.

Many beginner plans are designed for just finishing a half marathon – not aiming for a certain time. For that reason, most of these plans do not cover the full half marathon distance in training. 

Many of these training methodologies also offer training plans for intermediate to advanced runners. In these plans, a typical longest long run is 14 miles. 

However, as many runners know, your individual training may vary from generalized training plans – so let’s look into exactly how far you should run before a half marathon based on your current training and fitness.

The Science Behind Half Marathon Training Long Runs

A 2020 study published in the Scandinavian Journal of Medicine and Science in Sports studied how training volume and the longest run in training impacted half marathon performance and running injuries. They used a sample size of 556 half-marathon runners and ran statistical tests on based on questionnaires and race outcomes. The participants were 61% male, 39% female, and averaged five years of running experience. 

The statistical analysis revealed that the longest run of half marathon training did impact race outcome – without increasing the risk of a running injury. Half marathon runners who ran <15 km (<9.3 miles)  as their longest run finished in an average of 2:06:48. Those who completed long runs of 15-21 km (9.3-13 miles) finished in an average of 2:03:28. Only 26.3% of the participants ran >21 km (13 miles) in training – and had an average finish time of 1:51:31. 

 The longest long run also correlated with improved fatigue resistance. Fatigue resistance is the ability to continue to hold your pace/intensity for a prolonged time, even after you start to fatigue. Those who ran <15km and 15-21 km had a respective decline in pace of 10.3% and 12.1%. In comparison, the >21 km long run group only slowed down by 9.4%. 

Importantly, the longest long run in half marathon training is not the sole factor in determining performance. The same study reported a correlation between training volume and finish time. Additionally, training intensity (including any long run workouts) will also affect finish time. Still, the long run does contribute to performance in the half marathon. 

How Far Should You Run Before a Half Marathon?

The longest run before a half marathon will differ based on your training background and current fitness. A first-time half marathon runner and a seasoned marathoner will approach their training very differently. 

A novice runner (someone with less than a year of running or who has never run long distances) will want to carefully build their long run distance over 14-16 weeks. Gradually building up long run distance is a priority over the longest long run, since the athlete will be adapting their metabolic system, musculoskeletal system, and mindset to the demands of long runs. If you have run no more than 6 miles ever, you may gradually build up to the longest run of 10-11 miles (16-17 km) in training over those weeks. They may frequently repeat weeks at a certain distance before adding another mile. 

(That all said, I have coached individual novices to 13 miles before their race – but that was under close coaching supervision.)

If you have been running for a few years before your first half marathon, you may be able to do a longer long run during training. For example, a runner who can complete 8 miles (12-13 km) comfortably before they start training for their first half marathon may be able to reach 12-13 miles (19-21 km) in training before race day. 

Experienced runners who have completed half marathons before are better adapted to progress their long runs. These athletes are adapted to the biomechanical and metabolic demands of long runs. As a result, they can run over race distance in training. The practice of long runs longer than the half marathon (long runs lasting 14-16 miles) improves fatigue resistance and endurance. 

The frequency and exact distance of over-distance long runs depend on the athlete. An intermediate runner aiming for a 2 hour marathon may do one 14-mile long (23 km) run in training. An experienced 1:30 half marathoner may do multiple 14-16 mile (23-26 km) runs, plus long run workouts. 

In short: how far should you run before a half marathon?

  • Novice: 10-11 miles (16-17 km)
  • First-time half marathoner (but with a base): 12-13 miles (19-21 km)
  • Intermediate: 13-14 miles (21-23 km)
  • Experienced: 14-16 miles (23-26 km)

How to Run Farther in Half Marathon Training

If you struggle with long runs in half marathon training, you are not alone! 

  • Slow down: If you finish long runs feeling as if you cannot go another step, you may be running them too fast. Slow down! You cannot go too easy on long runs. If it helps, take walk breaks (while keeping your GPS recording). How slow should long runs be? Easy enough to chat with running buddies – or 1.5-3 minutes per mile slower than your goal pace.
  • Fuel enough: If you feel like you are dragging through long runs, or you spend the rest of the day on the sofa, you may be underfueling. I have seen so many athletes not fuel on half marathon long runs only because they think it’s just for marathon training! In reality, intra-run nutrition should be used on any run longer than 80-90 minutes. For most half marathon training long runs, you want about 40-60 grams of carbohydrates per hour. If you will be on your feet for 2.5+ hours, then you may want to try as high as 90 grams of carbs per hour. You can use gels, chews, whole foods, sports drinks, or a combination of these carb-rich sport nutrition options. Start fueling early and often, such as every 30 minutes during the run. (Learn more about how to fuel your long runs in this article.)
  • Hydrate: Dehydration does not enhance training adaptations! You will not become a mentally stronger runner by thickening your blood, stressing your nervous system, and overtaxing your body. Bring fluids with electrolytes on your half marathon long runs and drink appropriately for your sweat rate. If you struggle with hydration, consider doing a sweat test. 
  • Listen to an audiobook: Getting lost in a good story can help you run longer without getting bored. If you love novelty, use long runs to listen to new audiobooks. Or, if you are a comfort reader, revisit your favorites during your long runs.

You may also like: How to Feel Good on Your Long Runs

How Far Should You Run Before a Marathon?

A previous version of this article answers how far you should run before a marathon. Now, you can find more in-depth answers in these articles on how far you should run before a marathon and if you should limit long runs to three hours.

Want to work with a running coach for your next half marathon? Learn more about my coaching services here and schedule your initial consultation today! 

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26 Responses

  1. I think I ran 9-10 before my first half. Its been a while since I trained for a half (I usually run them while training for a full) so I usually feel comfortable completing the distance. It will be interesting when I start to think about doing another half at some point and need to build back up to double digits!

    1. I bet running a half while training for a full makes the distance much easier! I’m considering running a half during my marathon training – is it something you’d recommend?

      1. Yes but you also need to run atleast 20 to 24 miles during is crucial.the last 6 miles are all mental.ive run 7 marathons so good luck

        1. Agreed. I don’t think they really correlate that much, the marathon is all about those last 6-7 miles which can be brutal, esp for a more novice runner. The half feels more like an actual race and I’m not sure running a slower 18-22 miler pace 5-6 times would help. Would be better prepared for the half running more shorter distances at a faster pace and tempo. I ran a marathon first, then a half a few months later (with a 12 week training program). My half marathon pace was almost 2:00 minutes faster per mile than my marathon pace. Why? Well, of course you are going to run a bit slower, but also, those last 6-8 miles can be brutal mixed walking/hobbling and raise your total pace. They are different races really and I say this as just a novice runner. For more elite runners used to running it might not matter as much, but beware those last miles :D.

  2. I had a 22 miler last weekend and a 23 miler this weekend. That is definitely the furthest I’ve ever trained for a race. In past training cycles I was lucky if I ran 18. This training period has been much better!

  3. I’ve done one 11 mile run and my half marathon is 3 weeks away. I’m going to try for one 12-13 mile run before the race, just so I can feel confident enough on race day. Thanks for this advice.. it’s really helpful!! Racing a new distance is so scary… you have no idea what to expect.

    1. I’m glad you found it helpful! Even if you’re fitness is there, racing is so mental/emotional that extra confidence builders do help! New distances are scary – I’m already nervous/excited about my first marathon in October!

  4. Wish you had written this post before my first half back in 2013 😉 This is a great overview. I really loved working with my running coach up until my injury but I’m undecided what I’ll do in the future. The accountability really helped during the icy, cold, snowy winter months.

    Also, do I sense an announcement soon about becoming a running coach? Read through that “yet” in the disclaimer 🙂

    1. I do plan on signing up for an RRCA seminar once they announce their West Coast dates! It will probably be somewhere in the fall, but it’s something I’ve been wanting to do for almost a year now (once I decided PhD was not the path for me). 🙂

  5. I ran a 1/2 marathon at the end of may, and I will be running another one sept 20… in 4 days time. I have ran several long 2hour runs on the weekends during the summer along with 2or 3 weekday 10km runs.
    I did a 2hr run last weekend then a 45 mins slow run two days ago. I am just wondering what I should run in these remaining days before the race. Please let’s know.

    1. Hi, Annie! In days before you’re race it’s wise to cut back a bit on your mileage as a taper. If you do 2-3 10KM runs per week, try cutting back to 2-3 6-8KM at an easy pace during the days leading up to the race, on the same days as you did them throughout training. I hope this helps!

  6. My first half marathon is next weekend. My training peaked at just under 12 miles, which was yesterday. Prior to that it has been one long run a week with 2-3 three to six mile runs mixed in depending on how my body reacted. I did have a 10 mile race a week ago, which did teach me a valuable lesson about pace and keeping to my plan in the hysteria. I have received mixed opinions about adding the 12 miles yesterday, however I feel it did raise my confidence.

    1. That’s good that the 12 miles raised your confidence! Some may not suggest doing that long of a run so close to your marathon, but how you build your pre-race confidence can make such a difference. I hope you half goes well!

  7. I started to train for a half marathon and “fell of the wagon.” After four weeks of running four days a week and then month of not keeping up adequate runs (running once or twice a week with no long runs) I’m wondering if I could still do the half marathon in 9 days. My longest run was 10 miles. Definitely not ideal but wondering if its feasible.

    1. Several other factors play in: what is your general level of fitness? Were you doing cross-training during this time? To be honest, it may be in your best interest to not do the half – it may be feasible, but it will likely not be pleasant and you want to enjoy your first race! 4 weeks of training followed by 4 weeks of no long runs is not enough aerobic base – generally, 12-16 weeks of training is ideal for first-time half marathoners – and depending on how long you had been running before training for the half, you could place yourself at risk for injury. If you do chose to do the half, then I would encourage you to try run-walk intervals during the race to avoid hitting a wall. Best of luck on whatever you decide!

  8. More a question than a comment: I have been told that the distance you run in a week, you can pull together in a day. So e.g. if you run 10km a day for 3 days in a week, you could effectively run 30km in one day. How true is this?

  9. Hello, and thank you for this article. I’ve been training for The 2019 Disney World Marathon on January 13 th. for 6-months now. I have four 20-mile runs completed in training at about 9:50 minute miles. I’ve done these runs one every a week through December 2018, with the last one completed December 31, 2018. My weekly mileage at this point is at 40-miles per. My question is, do you think I’m ready? I’ve also recently purchased a Footpod Power Meter, and have considered using a power running plan instead of pace, to complete the marathon. What is your opinion on running with power, and can it help me finish the marathon without hitting that wall. Right now I feel a little bit of juice left after the 20-mile long run. Also, how much, if at all, should I reduce my mileage in the week before the race. I was planning on continuing the distances without anymore long runs till the race, with two complete days off for rest before.

  10. Hi Gerard,
    Without knowing much about your training, it is hard to say if you are ready or not for the marathon. Typically, if you can handle the mileage well and do well on the long runs, you can complete the marathon distance. I do not have any experience in training runners with power meters nor do I know much about using it to pace a race; my advice is to avoid using anything new on race day. If you have trained using pace, then use that for this race and try power meters for the next training cycle and race. Hitting the wall is a combination of many factors – pacing, fitness, and nutrition – so it is hard to predict whether one will hit it or not. Pacing yourself well, being prepared for the race distance, and properly fueling and hydrating will reduce your chances of hitting the wall. As for reducing mileage, typically running 50% of your normal mileage during race week works, but this will vary from runner to runner as everyone tapers differently. Good luck at your marathon!

  11. Hi
    I have the VLM in 6 weeks. Currently injured and haven’t run for a week (12 miles) and have to take another week of rest… what should my first run back be and What is an acceptable long run in the few weeks I have left in time for the marathon?

    1. Hi Maria! Without knowing too much about your training background and the type of injury you have, you want to start back with a long run likely similar to the last one you did before injury, if not shorter to test your injury. It is better to be cautious when returning from an injury. If you are injured, the best long run to do before the race is what you can safely manage. Ideally, before a marathon, you want to cover at least 3 hours of running in a long run, but you do not want to jump into this distance from injury if you have not done it before.

      1. Hi, I’m also running the London marathon but have injured my hamstring and glute. I am able to run, but not without pain. I ran 11 miles this week but was sore towards the end so am resting again now.
        I know you say you should run for 3 hours before a marathon, but when should you run this e.g. 2 or 3 weeks before? Also, if you’re not able to run this, what would be the least amount of miles needed to complete a marathon?

        1. Hi, without knowing what your training looked like in the months leading up, I cannot safely answer. You do not want to increase your volume too much in a short amount of time or you could be injured again. As for the least amount of miles to complete a marathon: it varies from runner to runner, but it is always better to be cautious when approaching a big race like a marathon when coming off of injury. You do want to speak to a PT if you are worried about running a full marathon on your injury.

  12. How about attempting a marathon distance 2 months out from the race just, I would be building up to that dummy run for 8 weeks, to know what exactly is going to happen to the body remove all doubt in the mind, recover for the whole of week 7 out, and continue prep 6 weeks out.
    I have run numerous half marathons and a 30km race once.
    Currently run around 45-60km a week for the last 15 months

    1. Due to the muscle damage of the marathon, it’s not recommended to cover the distance in training. The recovery is a week, which would result in a week of lost training (and mild detraining) during the pivotal weeks of the marathon. Plus, due to how supercompensation works, generally you want the longest run 2-3 weeks prior to the race.

      Now, if you were participating in two marathons, eight weeks out is a safe spacing, but that is not recommended for a first time marathoners.

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