Half Marathon Long Run: How Long Should Your Longest Training Run Be?

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Long runs are the bread and butter of any long-distance running, including the half marathon. They are where you build endurance and mental toughness, and prepare the body to go the distance. 

But how long should your longest half marathon long run be? 

The number of miles for your longest long run can vary widely based on your level of fitness and the time you have to train for your half marathon. But we are going to sort that out for you so you know what your longest long run should be for your half marathon training.

In this article, we will cover:

  • How long a half marathon is
  • How long does it take to train for a half marathon and how difficult is it to run one
  • Whether it is hard to go from a 10k to a half marathon
  • Whether you can you train for a half marathon 4 weeks and do you even have to train
  • How and when should you do your longest half marathon long run in training
  • How long should your longest long run be
  • Should you run 13 miles before running a half marathon
  • What is the shortest and longest long run you can do in half marathon training

So, let’s get started!

Half Marathon Training How Long Should Your Longest Long Run Be

How long is the half marathon?

The half marathon is 13.1 miles. It is half the distance of a marathon which is 26.2 miles. And in kilometers, a half marathon is 21k.

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

Assuming you have been doing some running including being about to run (at the very least) 3 miles without stopping, the average time it takes to train for a half marathon is 8 weeks. 

Most long runs will take place on the weekends, one time per week. These long runs will gradually build up each week until you run at least 8 miles or as many as 20 miles at a time in training.

Is it hard to run 13 miles?

Running 13 miles or a half marathon may seem difficult to non-runners. But with about 2-3 months of consistent running, it is possible for most people! 

And running a half marathon is MUCH easier than running a marathon, which is twice the distance at 26.2 miles or 42.2 kilometres.

Half Marathon Training How Long Should Your Longest Long Run Be 2

The average time to run a half marathon is about two hours and most people can train their bodies to endure the duration by carefully progressing the time they spend running week over week. 

Indeed, the half marathon is a challenging yet doable distance that doesn’t leave you zapped for weeks like the marathon can do!

Is it hard to go from 10K to half marathon?

Going from running a 10k to a half marathon is a natural progression and is a great way to increase your fitness! If you are able to run a 10k, you can train to run a half marathon in 4-6 weeks of additional training. 

Can I train for a half marathon in 4 weeks?

If you have a solid base of running at least 3 days a week and 15 miles per week, you can train for a half marathon in 4 weeks. 

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Do I have to do a long run to train for a half marathon?

Yes, you have to do a long run to train for a half marathon. That is because a long run in half marathon training prepares the body for running 13.1 miles by:

  • Building mitochondria and capillary density
  • Increasing VO2 max and blood volume
  • Strengthening tendons, muscles and bones; optimizing energy pathways
  • Improving neuromuscular fitness
  • Building mental toughness

Related: What to Eat Before a Long Run

If you don’t practice running for a long time before running a half marathon, you are setting yourself up for a world of hurt!

Half Marathon Training How Long Should Your Longest Long Run Be 4

Should my long runs be slow?

Yes! Your long runs should be run at an easy pace (about an effort of 6 out of 10 on the RPE scale). 

This is the effort zone where your body learns how to be efficient in using energy, building those energy factories called mitochondria, and increasing capillary density to supply your working muscles with more oxygen.

It also helps strengthen your musculoskeletal system safely, protecting you against injury.  

In more advanced training plans, or as you near your race, you may have some of your long runs done at tempo speeds or race pace.

Related: How You’re Screwing up Your Long Runs

When should you do your longest long run?

The longest long run in half marathon training is most often done about 2 weeks out from your half marathon. 

Some half marathon training plans will have you do your longest run just one week out from your half marathon race. 

The timing depends on when your taper, a progressive reduction in training volume, begins. 

Related: How to Taper for Marathon

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How long should your longest long run be in half marathon training?

Your longest long run for the half marathon should be between 10 and 12 miles, depending on the length of your training plan. Ideally, your long run should be at least 90 minutes long.

Here are specifics on how long your longest half marathon long run should be in your training:

  • However, more advanced runners (typically going for a time goal) may run up to 20 miles in their longest long run before a half marathon. 
  • Some runners, likely novice runners training to finish a half marathon, may only run 8 miles ahead of their half marathon. In many cases, these runners pick a race and train on a timeline rather than letting their fitness dictate when they run their race. It is ideal to train and then pick a half marathon race when you are ready. 
  • Runners running their first half marathon with a time goal, should run at least 13-14 miles ahead of their half marathon. These runners will benefit from some speed work including fartleks, tempos, goal race pace, and progression workouts, notes Norris. 
  • Newer runners running their first half marathon should spend some time gradually increasing their long runs up to 8 miles, adding one mile per week, before picking a half marathon training plan that begins long runs at this distance. 
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How much should I run a week to train for a half marathon?

Most runners will begin their half marathon training running 15 miles per week and gradually increasing their weekly mileage to about 25 to 30 miles per week. 

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

You should run at least 3 days a week to train for a half marathon, plus cross-training

In running, increasing frequency is more beneficial than duration. So, running 30 miles in four runs is better than running 30 miles in three days. Four is better than three days. Five is better than four. But always have a rest day!

Should you run 13 miles before a half marathon?

Unlike a marathon where you do NOT want to complete the full distance prior to the race, you can run 13.1 miles, the complete half marathon distance, before your half marathon. 

That is because running for 13 miles is not overly taxing on your body. If properly trained, you will be able to recover before your next long run or race. 

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Do I have to run 13 miles before a half marathon?

You don’t have to run 13 miles before you half marathon, points out certified running coach Laura Norris of Laura Norris Running.

“Many training plans take you to 12 miles before the half marathon. Tapering and the adrenaline of race day will carry you for the final 1.1 miles,” she advises.

What is the shortest long run you can do in half marathon training?

The shortest long run you can do in your half marathon training is 8 miles. This is not advised, however. 

If you are able to only run about 8 miles before your half marathon, know that much of your half marathon race will likely include walking or run/walk intervals. 

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What is the longest long run you can do in marathon training?

More advanced runners can run as long as 20 miles in their longest half marathon long run in their training. In many cases, these runners are using the half marathon race as part of their marathon training. 

Running for longer than a half marathon in your training will increase mental toughness, confidence, strength, and endurance.

Ideally, you want to start your training and then pick your race, giving you ample time to get fit and ready! 

Ready to supercharge your half marathon training?

Nail your longest long run with Marathon Handbook’s half marathon training resources!

Check them out:

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Whitney Heins is the founder of The Mother Runners and a VDOT-O2 certified running coach. She lives in Knoxville, TN with her two crazy, beautiful kids, pups, and husband. She is currently training to qualify for the 2024 US Olympic Trials marathon.

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