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

Plus, when should you plan your peak week long run?

Long runs are the bread and butter of any long-distance running goal, whether it be a full marathon or half marathon distance. They are where you build endurance and mental toughness and prepare your body for the goal distance. 

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

The number of miles for your longest long run will vary widely based on whether you are a first-time half-marathon runner or an experienced runner and how long you train for your race.

A ballpark figure for your longest half marathon long run is between eight and 20 miles. That’s quite a range! Keep reading to see where you fit into this range and what your longest half-marathon long run should be.

Half Marathon Training How Long Should Your Longest Long Run Be

How Long Does It Take To Train For A Half Marathon?

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

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

The average time to run a half marathon race distance is about two hours, and most people can train their bodies to endure this distance by gradually increasing their weekly mileage.

Do I Have To Do A Long Run To Train For A Half Marathon?

Yes, you must do a long run to train for a half marathon, in fact weekly long runs. A long run in half marathon training prepares the body for running 13.1 miles by:

  • Improving cardiovascular health1Impact of Running on Cardiovascular Health | International Journal of Sports, Yoga and Physical Activity, ISSN: 3005-5083. (2023). Internationalsportsjournal.com. https://internationalsportsjournal.com/index.php/sports/article/view/8
  • Increasing lung capacity
  • Increasing VO2 max and blood volume
  • Strengthening tendons, muscles, and bones; optimizing energy pathways
  • Improving neuromuscular fitness
  • Building mental toughness
  • Allowing the runner to optimize their fueling (gels), hydration (electrolytes), and dressing strategies
  • Becoming more comfortable running at a specific run pace or race pace

Related: What to Eat Before a Long Run

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

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

How Long Should Your Longest Half Marathon Long Run Be?

Your longest long run for the half marathon should be between 8 and 12 miles, depending on the length of your training plan andyour fitness level. Ideally, your long run should be at least 90 minutes.

Many runners do wonder, do I need to run 13 miles before a half-marathon? They feel that they absolutely need to reach that distance before race day to feel confident in getting to the finish line.

According to certified running coach Laura Norris of Laura Norris Running, you don’t have to run a 13 miler before your half marathon.

“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.

More advanced runners can run as long as 20 miles in their longest half-marathon long run in training. In many cases, these runners use 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.

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

  • Most 8—to 12-week half marathon training plans require runners to run a 12-mile run two weeks before their half marathon and reduce their volume before the race (aka taper). 
  • More advanced runners (typically those with a time goal and a specific half-marathon pace) 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 level dictate when they run their race. It is ideal to train and then choose 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, tempo runs, goal race pace sessions, and progression workouts as training runs.
  • Newer runners running their first half marathon should gradually increase 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. 
Half Marathon Training How Long Should Your Longest Long Run Be 5

When Should You Do Your Longest Half Marathon Long Run?

The longest long run in half marathon training is often done about two weeks before your half marathon. 

Some half-marathon training plans require you to do your longest run three or just one week before your half-marathon race. 

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

How Should I Pace My Long Runs During Half Marathon Training?

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

An easy run effort zone is where your body learns how to use energy efficiently, build those energy powerhouses called mitochondria, and increase 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 half-marathon training programs or as you near your race and do race-specific sessions, you may have some of your long runs done at tempo speeds or goal pace.

It’s important to follow a professional training plan so you can prepare as well as possible for your race, and not make anything up as you go along.

These plans will provide extra training tips, such as always performing a warm-up before your sessions and cooling down afterward and adding cross-training, strength training, and at least one rest day to your program to ensure you are reaping the maximum benefits of training.

Ready to supercharge your half marathon training?

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

Check them out:


Photo of author
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 US Olympic Trials marathon.

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