A good half marathon training plan takes about 12 weeks if you can already run 10km comfortably, and it is built on four runs a week: three runs of mixed intensity and duration, plus one long run that grows by roughly a kilometre a week to about 18km. Add strength training, a little speed work once your base is solid, a practised fuelling plan and a taper of two to three weeks. Most importantly, it has to match the runner you are today, not the one you hope to be on race day.
That last point is where most half marathons are won or lost. Say your goal is a sub-2 hour half marathon, and you decide to follow a 1:45 plan instead, to “give yourself a buffer”. It sounds clever. It isn’t. Your easy runs and long runs end up too fast, your interval sessions are out of reach, and you arrive on the start line tired or injured. Train for the goal you can realistically hit, and the faster time takes care of itself next season.
The half marathon is, in my opinion, one of the best distances there is. It’s challenging enough that you have to train properly, but it doesn’t hurt the way a marathon does. At 21.1km (13.1 miles), it rewards the runner who prepares sensibly.
In this guide:
- How long it takes to train for a half marathon
- Choosing a half marathon training plan for your goal time
- How many runs a week you need, and what a training week looks like
- Easy runs and why they are more important than you realise
- The long run: how far you really need to go
- Speed work: tempo runs, intervals and hills
- Strength training for half marathon runners
- Fuelling and hydration
- The half marathon taper
- Pacing your race
- The mistakes I see most often
- What comes after your half marathon
How long does it take to train for a half marathon?
Twelve weeks is the sweet spot if you already run regularly. Eight weeks can work for someone with a running background, but it leaves very little margin. If you are starting from scratch, give yourself longer.
My Half Marathon Training Roadmap is a 12-week plan, and that’s deliberate. Twelve weeks gives your muscles, tendons and ligaments time to adapt to the extra load, with room for a bad week, a cold or a work trip without your whole build falling apart.
Can you train for a half marathon in 8 weeks?
Yes, if you already have some running behind you. Between possible and advisable there is a very fine line, and the honest answer depends on your history. If you have been running a few times a week, eight weeks is doable as long as you build gradually and stay consistent. If you are brand new to running, the chances of getting there in two months without an overuse injury are slim, and I’d rather you pushed the race out.
With 8 weeks, consistency outweighs cramming in kilometres. Rather arrive slightly undertrained and injury-free than not make the start line at all. I’ve written a full guide on how to train for a half marathon in two months if that’s the window you have.
What if you’re starting from zero?
If you can’t yet run for 30 minutes without stopping, your first goal isn’t the half marathon. It’s building the habit and the base: running regularly, a few times a week, until a comfortable 10km is part of normal life. Then the 12-week build starts. This route is slower, but it’s the one that keeps you running for years rather than weeks.
Choosing a half marathon training plan for your goal
The right half marathon training plan is the one matched to your current fitness, and the best measure of that is a recent race or time trial. A 5km, 10km or previous half tells you far more than a time you’d like to run.
Every session in a well-built plan is pegged to your goal. Your easy pace, long run pace and interval targets all come from it, so if the goal is wrong, every run is wrong. This is why I build my plans around relative intensity: you choose the plan that matches your current performance, and the paces line up with your ability automatically.
Here is what the common goal times mean in terms of average pace. These are even-pace figures for the full 21.0975km (13.1 miles), so to dip under the time you need to be fractionally quicker.
| Goal time | Pace per km | Pace per mile |
|---|---|---|
| 2:30 | 7:06/km | 11:26/mile |
| 2:15 | 6:23/km | 10:17/mile |
| 2:00 | 5:41/km | 9:09/mile |
| 1:45 | 4:58/km | 8:00/mile |
| 1:30 | 4:15/km | 6:51/mile |
Look at the gap between 2:00 and 1:45: 43 seconds a kilometre. That’s a big jump, and it’s exactly why “training for 1:45 to make sure of 2:00” backfires. If your recent races point to 2:05, train for a sub-2:00 at a push, not for 1:45.
Is your first half marathon about time at all?
Not for me. The goal should simply be to finish strong and enjoy it. That changes the plan: you can leave out most of the speed work and focus on easy running and a steadily increasing long run. Your first time becomes your benchmark, and that’s when goal-time training really starts.
How many runs a week do you need for a half marathon?
Four runs a week is enough for most runners. You don’t need to (and shouldn’t) run every day. Four days gives you the volume to build endurance with enough rest between sessions for your body to adapt.
Remember that you get fitter in the recovery between sessions, not during them. The run applies the stress; the rest day is when your body repairs and comes back stronger. Skimp on the rest and you just accumulate fatigue.
What a half marathon training week looks like
Here’s how I structure a typical week for a runner who can already run 10km comfortably. Your four runs are a higher-intensity session on Tuesday, an easy run on Thursday, the long run on Saturday and an easy run on Sunday, with strength sessions on Monday, Wednesday and Thursday. That leaves Friday free to rest before the long run, and only one set of back-to-back running days.
| Day | Session | Purpose |
|---|---|---|
| Monday | Strength training | Injury resistance and running economy |
| Tuesday | Higher-intensity run | Speed and race fitness |
| Wednesday | Strength training | Injury resistance and running economy |
| Thursday | Easy run plus strength training | Aerobic base and strength |
| Friday | Rest | Recovery before the long run |
| Saturday | Long run | Endurance |
| Sunday | Easy run | Aerobic base and recovery |
For a first-timer coming up from 10km, aim for three runs of about 6-10km (4-6 miles) a week plus the long run. Once the long run reaches about 15km, you can start to stretch one of the other runs a little, up to about 12km at a push.
Can you add cross-training?
Yes, and it’s a good idea if you feel you should be doing more. Cycling and swimming build fitness without the pounding running puts on your legs. But keep at least one full day a week completely free of training, and if you feel tired all the time, the extra session goes first. One note: cross-training is not strength training. If you only have time for one, choose strength.
Easy runs: the part most runners get wrong
Most of your half marathon training should feel easy, and the most common mistake I see is runners running their easy runs too hard. That makes them too tired to run their hard sessions properly, so they end up training in a grey middle zone that does neither job well.
Easy runs build your aerobic engine while giving your muscles, tendons and ligaments time to repair and strengthen before the next hard session. You could run them a bit quicker and still get much the same physiological benefit, but you’d be beating up your body for no reason. Back off by 15-20 seconds per kilometre and you’re still working the right systems, and your legs recover faster.
How to tell if you’re running easy enough
- The talk test. You should be able to hold a full conversation, even laugh, without gasping. If you need to pause mid-sentence to breathe, slow down. Running alone? Talk to yourself. It feels odd, but it works.
- Heart rate. Easy running should sit at about 70-75% of your maximum heart rate, or around 80% of your threshold heart rate.
- The paces in your plan. If your plan is matched to your current fitness, its easy pace range is your guide. If that pace feels hard on a particular day, slow down further.
Don’t fall for “no pain, no gain”. If you finish every run shattered, you’re not training harder, you’re just recovering worse. For more detail, read my guide to training to pace and heart rate.
Not sure what easy should be for you? Use my free training zone calculator to work out your ideal training paces, so your easy runs stay easy and you’re fresh for the big sessions.
The long run: how far should you go?
Your longest run before a half marathon only needs to be about 18km (11 miles). You don’t need to run the full 21.1km in training. The cumulative kilometres in your week, every week, are what get you to the finish line. No single session or long run can define the success of a plan.
The simplest way to build it is to add about 1km to your long run each week. Start at a distance you can comfortably manage, say 11km, then 12km the following week, and so on until you reach about 18km. Then back off so your legs can freshen up for race day.
Your long runs are where you build endurance, teach your body to be on its feet for a long time and get used to the distance mentally. They’re also your rehearsal for race-day fuelling, so use them to experiment with what you eat and drink.
How fast should your long run be?
Slower than race pace. It’s a common misconception that you should do all your training at the pace you plan to race. Long, slow running builds the endurance that carries you through the final 5km. The race-pace work comes from the other sessions in your week.
Distance or time?
Time is fairer. An easy 10km takes a fast runner around 55 minutes and a slower runner 75-80 minutes, which is a big difference in time on your legs. If you’re on the slower side, build your long run by duration rather than distance, adding about 10 minutes a week. If a run starts to feel uncomfortable at 30 minutes, cap it there for now and build from that point.
How fast can you increase your weekly kilometres?
Gradually. My rule of thumb is no more than about a 10% increase in total weekly time or distance from one week to the next. If you ran 16km (10 miles) this week, aim for about 18km (11 miles) next week, not 25km. The slower the progress, the more permanent the change.
Speed work: tempo runs, intervals and hills
Speed work makes you faster over 21.1km, but only once you have a solid base, and only one session a week. If this is your first half marathon and your goal is to finish, you can skip it entirely and focus on easy running and the long run.
For runners chasing a time, there are three tools.
Tempo runs
A tempo run is a sustained run at a comfortably hard effort, close to your lactate threshold. For a half marathon, I prescribe tempo runs of between 7km and 12km (4-7 miles), with faster runners at the longer end of that range. It should feel like an upbeat song, not an all-out effort, and leave you feeling strong rather than spent.
In a 12-week build, two tempo runs are enough: the first around weeks 5-6, the second three weeks later, 3-4 weeks out from race day. They build confidence and give you a chance to practise taking a gel or a drink at close to race effort, which is harder than it sounds. My guide to heart rate and threshold training goes deeper.
Intervals
Intervals alternate short, fast efforts with recovery. They develop speed and the ability to hold a hard pace, but they carry a higher injury risk, so warm up properly and only add them once your body is conditioned for them. Keep them pegged to your realistic goal: if you can’t hit the interval targets, the goal is probably too ambitious.
Hill repeats
Hills are speed work in disguise. Hill repeats build speed and strength at the same time, so in a week where you’d do one quality session, they’re a good alternative to intervals: one or the other, not both. If your race has a few climbs, they’re especially worth including.
How hard should your hard sessions be?
Run easy really easy, and when you run hard, really run hard. That polarised approach is what I build into my plans, and it only works if the easy days are truly easy.
Strength training for half marathon runners
Strength training makes you a more efficient runner and a more resilient one, and it belongs in every half marathon training plan. Two sessions a week is the target.
That isn’t just my opinion. A systematic review by Blagrove, Howatson and Hayes in Sports Medicine found good evidence that strength training improves running economy by 2-8% compared with control groups, along with time-trial performance. The authors recommend adding two to three strength sessions a week.
Running economy is how much energy it costs you to run at a given pace. Improve it and the same pace feels easier, which is exactly what you want at 17km. You don’t need a gym: bodyweight work at home, done consistently, gets most runners a long way. That’s why my Half Marathon Training Roadmap includes strength and conditioning plans for beginners and advanced athletes, all of which you can do at home without special equipment.
If you’re new to strength work, start here: my free strength plan for runners is one session a week at home with no expensive gym equipment, with clear descriptions, the exact reps and short videos for every exercise.
Fuelling and hydration for your half marathon
Practise your race-day fuelling and drinking in training, and never try anything new on race day. That single rule prevents most of the stomach problems and energy crashes runners blame on the distance.
Do you need gels for a half marathon?
It depends on how long you’ll be out there. According to a review by Asker Jeukendrup in Sports Medicine, small amounts of carbohydrate, or even just a carbohydrate mouth rinse, can benefit performance in efforts of about an hour, while up to about 60g per hour is recommended for exercise lasting 2-3 hours.
In practice, the quicker you’ll finish, the less you need. If you’ll be out there for two hours or more, some carbohydrate during the race usually helps. Gels are convenient, but they aren’t compulsory, and some runners simply don’t get on with them. What matters is finding what works for your body, and the only place to find that out is in training.
How much should you drink?
Enough, but not too much. Overdrinking is a real risk. The international consensus statement on exercise-associated hyponatraemia, published in the British Journal of Sports Medicine, identifies drinking more low-sodium fluid than your body needs as the main cause of this dangerous drop in blood sodium. Practise drinking in training, use your long runs to learn what you need, and don’t force fluids just because there’s a water table.
Practise at race effort
Eating and drinking on a slow long run is easy. At race pace, when you’re breathing harder, chewing or even swallowing a gel can be a struggle. Use your tempo runs to find out whether your plan still works at speed.
The half marathon taper
Taper for two to three weeks before your half marathon. You cut back the volume of your training so your body can absorb the work you’ve done and arrive fresh, but you don’t stop training altogether.
The research backs a short, sharp taper. A meta-analysis by Bosquet, Montpetit, Arvisais and Mujika in Medicine & Science in Sports & Exercise found the most effective taper lasted two weeks, reduced training volume by 41-60%, and kept intensity and training frequency the same.
Here’s how that looks in practice:
- Two weeks out: bring your long run down to about 1 hour 30 minutes.
- Race week: keep running on your usual days, but make the runs short and easy, around 30 minutes.
- Intensity: keep a little sharpness, with a few short efforts at race pace, but nothing that leaves you sore.
- Food: you’re burning less, so manage portion sizes rather than eating as if you’re still in peak training.
- Sleep: prioritise it. An extra hour a night in the final weeks helps your body and your immune system.
Tapering does NOT mean doing nothing. Runners who stop completely in race week often feel flat and sluggish on the day. For the final month, read my guide to the final 4 weeks before race day.
Pacing your half marathon
Aim for even splits, and start controlled: no faster than your goal pace. Starting too fast is the most expensive mistake you can make in a half marathon, because the early adrenaline hides how hard you’re working until it’s too late to fix.
Use the pace table above to know your number, and practise it in training so it feels familiar. Then plan for the course. A hilly first half, a headwind or a hot day all mean adjusting to effort rather than chasing a pace on your watch.
A simple pacing plan
- The opening kilometres: hold back. Let the crowd go and settle into your goal pace, not faster.
- The middle of the race: stay relaxed and even, and take your fuel and drinks as practised.
- The final 5km: if you still feel good, this is where you can gradually lift the effort.
Even pacing is what you’re aiming for. If you finish feeling like you had a little left, that’s a far better problem to have than walking the last 3km.
The half marathon training mistakes I see most often
Most half marathon disappointments come from a handful of avoidable mistakes, and almost all of them involve doing too much, too soon.
- Choosing an unrealistic goal. Every pace in your plan flows from it, so an inflated goal makes every run too hard.
- Running easy runs too fast. You end up tired for the big sessions.
- Building too quickly. Big jumps in weekly volume are a fast track to an overuse injury.
- Skipping the long run. It’s the session that builds the endurance you need for the final kilometres.
- Skipping strength training. It’s what keeps you injury-free and makes you more efficient.
- Ignoring pain. Pain is not a normal part of training. If something hurts, stop and let it settle. If pain persists or gets worse, see a physiotherapist or doctor.
- Not recovering properly. Fatigue carried from one session to the next eventually catches up with you.
- Trying new food or kit on race day. Everything you use on the day should have been tested on a long run.
- Not following a plan. Without structure, it’s too easy to do too much one week and too little the next.
It’s better to arrive on the start line slightly undertrained and healthy than nursing an injury. You can’t race well from the side of the road.
Going from 10km to 21km
If you can run 10km comfortably, a half marathon is well within reach in 8-12 weeks. Hopefully you’re already running three or four times a week, which means the base is there.
Keep your three shorter runs at 6-10km and add about 1km a week to your fourth run, the long one, until you reach about 18km. Then ease off for the taper. That’s it. It’s simple, but simple works.
If you’re not quite at 10km yet, my 10km Training Roadmap is the right first step.
What comes after your half marathon?
Recover first, then decide what’s next. Give yourself a few easy days after the race, and only reintroduce hard sessions once your legs feel normal again.
For many runners, the half marathon is a stepping stone to the full 42.2km. It’s a natural progression, and the habits you’ve built here (easy running, a steady long run, strength work and practised fuelling) are exactly what marathon training needs, just with more patience. Read my complete guide to marathon training, and when you’re ready, my Marathon Training Roadmap takes you there.
Others fall in love with the half itself and want to keep getting faster at it. That’s a great goal too. The half rewards consistent, sensible training perhaps more than any other distance.
Half marathon training plan FAQs
Do you need to run 21km before your half marathon?
No. A long run of about 18km (11 miles) is enough. The cumulative training you do across the weeks is what carries you to the finish, and race-day adrenaline plus a proper taper will take care of the last few kilometres.
How many kilometres a week should you run for a half marathon?
For a first-timer coming up from 10km, a typical week is three runs of about 6-10km (4-6 miles) plus a long run that builds to around 18km (11 miles). Faster and more experienced runners will run more, but the number matters less than building it gradually and staying consistent.
When should you stop training before a half marathon?
You don’t stop. You taper. Start cutting back two to three weeks before race day, bringing your long run down to about 1 hour 30 minutes two weeks out, then running short, easy 30-minute runs in race week.
Get the right half marathon training plan for you
The best half marathon training plan is one that matches where you are today, tells you exactly what pace each session should be, builds you up gradually and includes the strength work most runners skip. That’s what I built my Half Marathon Training Roadmap to do.
It’s a step-by-step 12-week plan with options for every ability, whether you’re aiming for a sub-2 hour half marathon or simply to finish in one piece. Every session is broken down with pace targets, your long runs are scheduled for you, and strength, conditioning, warm-up and stretching routines are included, all doable at home. If you want to run your best 21km without guessing, choose your Half Marathon Training Roadmap here.
Train for the runner you are, and you’ll become the runner you want to be.
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