Half Marathon Training, Decoded

The half marathon is the race a lot of runners circle after their first 5K or 10K, and for good reason. At 13.1 miles it’s long enough that you can’t fake it on race day, but short enough that the training fits inside a normal week instead of taking it over. Participation keeps growing too: Running USA’s review of 2025 found growth at the country’s top races across every major distance, the half included (Running USA).

What makes half marathon training confusing isn’t a lack of information. It’s that every coach, app and running club has a plan, the plans disagree on things that sound important, and almost none of them explain why they’re built the way they are. This guide covers the parts that every good plan shares, the places where the respected coaches genuinely disagree, and how to turn all of it into a plan you can actually follow. Each section links to a deeper guide when you want the full picture.

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

Most established half marathon plans run 12 to 18 weeks, and where you land in that range depends far more on what you’re running today than on how fast you want to finish.

Hal Higdon’s Novice 1, one of the most widely used first-half plans, is 12 weeks long and assumes you can already run 3 miles, three to four times a week, before week one (Hal Higdon). The Hansons’ beginner half marathon plan takes 18 weeks and builds considerably more volume along the way (Hansons Coaching). The free 18-week half marathon plan here sits between them, starting from runners who can run 3 to 4 miles comfortably and already log 12 to 18 miles a week.

If you can’t run 3 miles without stopping yet, the honest answer is that your training starts before the plan does. A few weeks of consistent, easy running to get to that starting line will do more for your race than squeezing into a plan you’re not ready for. If you’re already running regularly and have about three months, the 12-week half marathon plan guide walks through which programs fit that window and which ones don’t.

What a half marathon training week looks like

Strip away the branding and almost every half marathon plan is built from the same four pieces, arranged across five or six days. What changes from plan to plan is the proportion.

Easy runs. Most of your running should feel easy enough to hold a conversation. Stephen Seiler’s research on how elite endurance athletes train found that roughly 80 percent of their sessions are done at low intensity, with the hard work kept to the remaining 20 percent (Seiler, 2010). Higdon gives beginners the same instruction in plainer terms: if you can’t talk while you run, you’re going too fast, and heart rate users can aim for 65 to 75 percent of maximum (Hal Higdon). Easy days are where the aerobic engine gets built, and they’re also the days most runners quietly run too hard. The easy run guide covers how slow is slow enough.

The long run. One run a week gets longer as the plan goes on, and it’s the session most plans protect above everything else. Higdon’s Novice 1 builds the long run from 4 miles to 10 before race day, while the Hansons’ beginner plan tops out at 12 miles and runs that distance four separate times (Hal Higdon; Hansons Coaching). Neither asks you to cover 13.1 miles before the race. Jack Daniels caps an easy long run at 25 to 30 percent of your weekly mileage or 150 minutes, whichever comes first (VDOT O2), which keeps the long run from swallowing the rest of the week. The long run guide goes deeper on pacing and distance.

Quality days. One or two days a week carry the harder work, and for the half marathon the most important of these is threshold running. Daniels defines threshold pace as an effort you could race for roughly an hour, run as a steady 20-minute tempo or as cruise intervals like repeated miles with short rests, and he limits it to about 10 percent of weekly mileage (VDOT O2). Pete Pfitzinger builds half marathon training around the same lactate threshold work, adding short reps at 3K to 5K pace to sharpen (Runner’s World). If “tempo” and “threshold” still blur together, the tempo run guide untangles them.

Rest and cross-training. Higdon’s beginner plan takes Monday and Friday off and adds an optional cross-training session on Saturday, with swimming, cycling and walking all on the list (Hal Higdon). Rest days aren’t a gap in the plan. They’re when the training actually turns into fitness, which is why the rest day guide treats them as a workout of their own.

How many miles a week do you need?

Less than the internet tends to suggest, especially for a first half. Higdon’s Novice 1 peaks at roughly 20 to 23 miles a week (Hal Higdon). The 18-week plan here peaks at 33 to 42 miles in week 16, depending on which end of its ranges you run. The Hansons’ beginner plan reaches 47 miles at its peak (Hansons Coaching). All three will get a healthy runner to the finish line. The higher-volume plans are built for runners who want to race the distance rather than complete it.

How you get to your peak matters more than the peak itself. The famous “10 percent rule” doesn’t hold up as well as its reputation: in a randomized trial of 532 novice runners training for a 4-mile race, a graded program built on it produced the same injury rate as a standard plan, about 20 percent in both groups (Buist et al., 2008). Big jumps still carry risk, though. A year-long study of 874 new runners found that those who increased weekly distance by more than 30 percent over two weeks appeared more vulnerable to overuse injuries like runner’s knee and IT band syndrome (Nielsen et al., 2014). The practical version is to build steadily, take the down weeks your plan gives you, and back off when something hurts in a way that changes how you run. When to take a break from running covers how to tell the difference.

Where the coaches disagree: half marathon pace

The most interesting split in half marathon training is over a simple question: should you practice running at your goal pace?

Jack Daniels mostly says no. His system trains the paces around the half marathon instead of the race pace itself: easy running, marathon pace, threshold, intervals at roughly the pace you could race for 10 to 12 minutes, and short repetitions at mile pace (VDOT O2). The logic is that half marathon pace sits between threshold and marathon pace, so training both sides of it covers the physiology.

The Hansons build their plan around exactly what Daniels leaves out. Their beginner half marathon plan includes a mid-week run at goal half marathon pace for 13 straight weeks, growing from 3 miles to 6, and later swaps the faster intervals for repeats at goal pace minus 10 seconds per mile (Hansons Coaching).

Greg McMillan lands in between. He places half marathon pace between your lactate threshold, roughly your one-hour race pace, and your aerobic threshold, roughly the pace you could hold for two and a half hours. Because it sits in that gap, it’s hard to judge by feel, so he tests it in training: 2 to 3 × 3 miles at goal pace about eight weeks out, 2 × 4 miles about four weeks out, and a 6- to 8-mile run at goal pace two to three weeks out (McMillan Running). David Roche, meanwhile, starts almost every training cycle with strides and short fast running before anything long and steady, on the idea that you learn to run fast first and then learn to hold it for longer (Andrew Skurka).

What this means for you is less dramatic than the debate suggests. Every one of these approaches puts most of your running at an easy effort, includes threshold work and builds a long run. The disagreement is about the last 10 percent of the plan. If you like knowing exactly what race pace feels like, a plan with goal-pace runs will suit you. If you’d rather train the systems and trust the race to come together, Daniels’ approach works. Why most half marathon training is wrong goes further into what the research says about each approach.

Set your paces from a race, not a goal

The most common mistake in a training plan has nothing to do with which plan you pick. It’s running the workouts at the pace you hope to race instead of the pace your fitness supports today.

Daniels’ VDOT system is built to prevent exactly that: you enter a recent race result and it gives you every training pace from easy to repetition (VDOT O2). McMillan recommends the same starting point, ideally using several recent races at different distances so one great or terrible day doesn’t skew the numbers. If you only have a 10K, his rule of thumb is to double your 10K time and add 10 to 15 minutes to estimate your half marathon (McMillan Running).

Training off your current fitness keeps easy days easy and makes hard days hard in the right way. As you get fitter, retest with another race or time trial and your paces move with you. The pace calculator on the 18-week plan does the math for you.

The phases of a half marathon plan

Most plans move through the same arc even when they label it differently.

Base. The first several weeks are mostly easy mileage, a growing long run, and short, relaxed speed like strides. The goal is consistency: getting your legs used to running five days a week before you ask anything hard of them.

Development. The middle of the plan adds structured workouts, usually threshold running plus intervals. Mileage keeps climbing and the long run keeps growing.

Race-specific. In the last month or so before the taper, the work starts to look more like the race itself. That might mean goal-pace runs, longer threshold sessions or fast-finish long runs, depending on whose plan you’re following. McMillan points out that the hardest part of a half marathon is the final 3 to 4 miles, which is why this phase includes work done on tired legs (McMillan Running).

Taper. The last one to two weeks cut volume while keeping some intensity. A meta-analysis of 27 tapering studies found the best results from a two-week taper that reduced training volume by 41 to 60 percent while keeping intensity and the number of sessions the same (Bosquet et al., 2007). The urge to squeeze in one more workout during the taper is normal, and it’s the one to ignore. Trust the work is written for the marathon, but its day-by-day race week applies to the half almost exactly.

Fueling your training and the race

The half marathon lands right in the range where fueling starts to matter. In the Vienna race data covered below, even the fastest quarter of men averaged about 13 km/h, roughly a 1:37 half, which puts nearly everyone past the 90-minute line that sports nutrition guidelines use.

The joint position stand from the American College of Sports Medicine and two dietetics organizations recommends 7 to 12 grams of carbohydrate per kilogram of body weight in the 24 hours before an event shorter than 90 minutes, and 10 to 12 grams per kilogram per day for the 36 to 48 hours before events longer than that (The Feed, summarizing the ACSM position stand). During exercise lasting one to two and a half hours, the recommendation is 30 to 60 grams of carbohydrate per hour (Ned Tijdschr Geneeskd, 2015). Check the carbohydrate count on the gel or drink you use and work back to that range.

The part that gets skipped is practice. Runners who’ve been through a training cycle are quick to name underfueling as a mistake they wish they’d fixed sooner, from skipping food before long runs to running out of energy late (r/running). Use your long runs to try the breakfast, the gel and the timing you plan to use on race day, so nothing on race morning is new.

Race day: how to pace a half marathon

Almost everyone slows down in the second half. An analysis of 133,268 half marathon finishers at the Vienna City Marathon from 2006 to 2018 found that runners in every performance group ran a slower second half. The fastest runners paced most evenly, slowing about 3 percent, while the slowest quarter slowed about 6 percent (Ristanović et al., 2023).

The pattern behind those numbers shows up in race reports all the time: a runner gets swept up in the start, finds themselves well ahead of plan in the first few miles, and is fighting to hold on by mile 10 (r/TurtleRunners). The fix is unglamorous. Run the first 2 to 3 miles slightly slower than goal pace, settle into goal pace through the middle, and save whatever you have left for the last 5K. McMillan’s advice is to set a realistic goal based on your training rather than wishful thinking, then adjust on the day for how you feel, the weather and the course (McMillan Running).

Common half marathon training mistakes

When experienced runners trade stories about what they’d do differently, the same handful of mistakes keeps coming up (r/running).

Running easy days too hard. It’s the most common one, and it’s sneaky because it feels productive. Easy runs at a moderate effort leave you too tired to hit your workouts properly, so the whole week ends up medium.

Building mileage too fast. Jumping volume because the plan feels easy in week three is how Achilles and knee problems start. The plan’s ramp is there for your tendons, not your lungs.

Training at goal pace instead of current fitness. Workouts set from a goal time turn every quality day into a race. Set paces from a recent result and let them move as you get fitter.

Skipping fuel on long runs. Long runs are your chance to practice race-day nutrition. Running them on empty teaches you nothing about how your stomach will handle a gel at mile 8.

Running through injury. A niggle that changes your stride is a reason to take a day or two, not to push through. A few missed days rarely cost a race. A few missed weeks often do.

How to choose a half marathon training plan

With the pieces above, choosing a plan comes down to three honest questions: how much are you running right now, how many days a week can you give it, and do you want to finish or race?

If you’re running 12 to 18 miles a week, have five days available and about four months, the free 18-week half marathon plan was built for you. It uses mileage ranges instead of fixed numbers, sets paces from a recent race, and exports to your calendar. If you have closer to three months, or only three days a week, the 12-week plan guide compares Higdon, Pfitzinger and FIRST and matches each to the life it fits. And if you haven’t picked a race yet, building a better race calendar helps you choose one that gives the training room to work, and the race lottery calendar tracks when the big-city races open registration.

FAQ

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

Most plans run 12 to 18 weeks. If you can already run 3 miles three or four times a week, 12 weeks is enough for a first half. If you want more room to build mileage, or you’re aiming to race rather than finish, 16 to 18 weeks gives you that.

How many miles a week should I run for a half marathon?

Beginner plans peak around 20 to 25 miles a week, and plans built to race the distance often peak between 35 and 50. Your current mileage matters more than the peak: start a plan close to what you already run and build steadily from there.

How long should my longest training run be?

Most plans top out between 10 and 12 miles, which is enough. You don’t need to run 13.1 miles before race day, and keeping the long run to about a quarter of your weekly mileage protects the rest of your week.

Can you run a half marathon without training?

Some people finish one without training, but it’s a good way to get hurt and have a miserable morning. Even a few weeks of consistent easy running and a couple of longer runs will change the experience completely.

What pace should I run my first half marathon?

Use a recent 5K or 10K result to estimate it, then start the first 2 to 3 miles a little slower than that. Most first-timers lose more time by starting too fast than they ever gain by running hard early.

What should I eat before a half marathon?

Eat a familiar, carbohydrate-heavy dinner and breakfast, and lean toward carbs for a day or two beforehand if you expect to be out there longer than 90 minutes. Take in 30 to 60 grams of carbohydrate per hour during the race, and practice all of it on your long runs first.