Last Updated: 18 October 2026
A half marathon training plan is the bridge between comfortable 10k running and a confident 13.1 miles, and autumn is the perfect time to build it. Entries for spring 2027 races are opening, for events such as the London Landmarks Half Marathon and local spring halves across the UK, and twelve weeks of steady winter training will land you on a spring start line ready.
This guide is an original, general plan for healthy adult runners who already run regularly. It sets out who the plan suits, the weekly pattern, a full twelve-week schedule in base, build, peak and taper phases, plus fuelling, strength work, injury prevention and race-day pacing. Half marathon fitness is built quietly, run by run, not in one heroic week.
What is a half marathon training plan? A half marathon training plan is a structured twelve-week schedule that builds your long run gradually towards 10 to 11 miles, mixes easy running with one weekly quality session, and finishes with a taper, so you can cover 13.1 miles confidently on race day.
Half Marathon Training Plan Explained: Who This Plan Is For
A half marathon training plan is a progressive running schedule that increases your weekly distance and the length of your longest run in small, planned steps over about twelve weeks, balancing easy running, one harder session and rest, so that endurance grows without breakdown.
This half marathon training plan suits runners stepping up from shorter distances: people who can already run a 5k comfortably, have completed a 10k, or run two or three times a week and want a first half marathon in spring 2027. It assumes you can run for around 40 to 50 minutes without stopping and have held that routine for at least the past month. That base matters, because twelve weeks is long enough to extend a 10k runner to 13.1 miles, but not long enough to start from the sofa safely.
If you are not there yet, build in stages. Spend a few weeks enjoying regular 5k running — many runners use their local parkrun as a friendly weekly marker — then follow our 10k training plan to reach the fitness this plan assumes. A spring half will still be there once your base is ready.
Before you start, a word about health. This article is general fitness information, not medical advice. If you are new to exercise, or you have a heart condition, joint problems, asthma or any long-term health condition, or you are recovering from injury or surgery, or you are pregnant or have recently given birth, see your GP before following any half marathon training plan, and follow their advice over anything written here.
The Weekly Pattern: Easy Runs, One Quality Session, the Long Run and Rest
Every week of this half marathon training plan uses the same simple pattern, which keeps twelve weeks manageable around work and family. Most weeks contain four runs: two or three easy runs, one quality session and one long run, with rest or gentle cross-training on the other days. The days can flex, but never place the quality session and the long run on consecutive days, because fitness is built during recovery.
- Easy runs: relaxed running at a pace where you can speak in full sentences. Most of your weekly mileage should feel like this; easy running builds the aerobic engine that carries you through the later miles.
- Quality session: one session a week with a purpose — short intervals at a brisk effort with easy recoveries, or a tempo run at a comfortably hard pace you could sustain for roughly an hour. One is enough.
- Long run: the cornerstone session, run slowly and extended gradually across the twelve weeks. It teaches your body to use fuel efficiently, your legs to endure, and your mind that the distance is survivable.
- Rest and cross-training: at least one full rest day each week, plus optional gentle cycling, swimming, yoga or walking. Rest is part of training, not a break from it.
- Strength work: two short sessions a week, covered in detail below, to keep hips, knees, calves and ankles resilient as the long run grows.
Effort, not pace, is your guide throughout. Easy days must stay genuinely easy, because the classic mistake at this distance is running everything at the same medium-hard effort, which produces tiredness without progress. If you have followed our marathon training plan before, you will recognise the same principles here, scaled down to a smaller weekly load.
The 12-Week Half Marathon Training Plan, Week by Week
Here is the complete structure of this half marathon training plan, in four phases: weeks 1 to 4 build your base, weeks 5 to 8 build endurance, weeks 9 to 11 are the peak, when the long run reaches 10 to 11 miles, and week 12 is the taper. Distances are guides for a runner whose easy pace is roughly ten to eleven minutes per mile; slower runners can cap the long run at around two hours and fifteen minutes.
| Week | Long run | Focus |
|---|---|---|
| Week 1 | 5 miles | Base: settle into four runs a week, all easy apart from short strides |
| Week 2 | 6 miles | Base: first tempo session, 10 minutes at comfortably hard effort |
| Week 3 | 7 miles | Base: intervals introduced, such as 6 x 2 minutes brisk with easy recoveries |
| Week 4 | 5 miles | Base: easier week, lower mileage to absorb the first block |
| Week 5 | 8 miles | Build: long run steps up, tempo extends to 15 to 20 minutes |
| Week 6 | 9 miles | Build: practise taking a gel or chews on the long run |
| Week 7 | 10 miles | Build: first double-figure long run, quality session at half marathon effort |
| Week 8 | 7 miles | Build: easier week, check shoes, kit and any niggles |
| Week 9 | 10 miles | Peak: long run with the final 2 miles at a steadier effort |
| Week 10 | 11 miles | Peak: longest run of the plan, full race-day fuelling rehearsal |
| Week 11 | 10 to 11 miles | Peak: final long run, then mileage begins to fall |
| Week 12 | 6 miles early in the week | Taper: short, easy running only, then race day — 13.1 miles |
The peak long run of 10 to 11 miles is deliberately short of the full 13.1 miles, which is 21.1 kilometres. You do not need to cover the whole distance in training: consistent weekly mileage, a long run close to race distance and the energy of race day carry runners through the final two miles.
If life interrupts — illness, work or an icy week in January — do not cram missed runs into the following days. Resume where you left off, repeat the last completed week if you lost more than a few days, and shorten the long run rather than skipping the week. For more detail on sessions and pacing, the guides at Runner’s World UK are a useful companion. Finishing healthy matters more than finishing perfectly.
Fuelling for Long Runs and Race Day
Fuelling is a skill, and the long run is where you practise it. For runs under about an hour, normal meals and water are enough for most people. As the long run passes 90 minutes, your stored carbohydrate begins to run low, and taking on fuel during the run — an energy gel, chews or jelly sweets — helps you finish strongly instead of fading. Start practising from week 6, in small amounts, so your stomach learns the routine well before race day.
Before a long run, eat a normal carbohydrate-based meal two to three hours beforehand: porridge with banana, toast with jam, or a bagel all work well. Avoid rich, very high-fibre or unfamiliar food on long-run mornings. During the run, general guidance is to take on carbohydrate little and often rather than in one large dose late on, and to drink to thirst, carrying water or planning a route past refill points on the longest efforts.
After the long run, eat within a couple of hours: carbohydrate to refill energy stores and some protein to support muscle repair. An ordinary meal does this perfectly well. One rule covers everything here: never try a new gel, drink or breakfast on race day. If it has not been tested during this half marathon training plan, it does not belong in your race.
Strength Work and Injury Prevention
Strength work is the half marathon runner’s insurance policy, and it needs only fifteen to twenty minutes, twice a week. Work through simple exercises such as squats, split squats or lunges, calf raises, step-ups, glute bridges and dead bugs for the trunk. Bodyweight is enough for most runners stepping up from 10k; add a rucksack or dumbbells gradually if the exercises become easy. Schedule it on an easy day or after a run, never the day before your long run.
Prevention is mostly habits rather than heroics. Increase the long run in the small steps shown in the table, keep easy days easy, replace worn shoes in good time, and treat sleep as part of the plan. Normal training produces general tiredness, heavy legs after a long run and mild soreness that eases within a day or two — those sensations are the plan working, not a warning sign.
- Sharp or localised pain in one specific spot, especially in the foot, shin, Achilles tendon or knee, that is there at the start of every run.
- Pain that changes how you run — limping, shortening your stride or avoiding putting weight through one side.
- Swelling, numbness or pins and needles that does not settle after a few days of rest.
- Pain getting worse week by week despite easier weeks and reduced mileage.
- Feeling unwell: chest pain, unusual breathlessness, dizziness or illness below the neck, such as a chesty cough or fever, are reasons to stop and rest, not train through.
The response to a warning sign is rest first, then advice if it persists. A few missed days costs almost nothing across twelve weeks; running through a developing injury can cost you the race. If pain persists for more than a week, or you are unsure about a symptom, see your GP or a physiotherapist rather than relying on general advice, including this article.
Training Through Dark UK Evenings: Autumn and Winter Realities
A twelve-week half marathon training plan aimed at a spring race is, in practice, a winter plan, and British winter has its own rules. Much of your running will happen before dawn or after work, in the dark, so visibility is non-negotiable: wear hi-vis or reflective clothing on every dark run, add a headtorch or chest light on unlit routes, and tell someone your route when you head out alone. Being seen matters more than looking stylish.
Cold, wet and icy weather will test the plan, so build in flexibility. Swap sessions within the week when frozen pavements make a quality session unsafe, choose gritted, well-lit routes on the worst evenings, and layer clothing you can adjust as you warm up. A treadmill is a perfectly good alternative for easy miles and even intervals when conditions are genuinely poor; a session completed indoors always beats one skipped while waiting for perfect weather.
Winter also hides dehydration, because you feel less thirsty in the cold while still sweating under layers, so make drinking across the day a deliberate habit. Finally, look after your feet: trim toenails, deal with hot spots before they become blisters, and test anti-chafe balm and race-day kit on long runs well before spring.
Race Week and Race Day: Pacing and the Negative Split
By race week, the work of this half marathon training plan is done. Nothing you run now can add fitness, but plenty can subtract it, so the final days are about rest, organisation and familiar food. Follow these steps for a calm race morning and a well-paced 13.1 miles.
- Trust the taper. Keep only the short, easy runs in week 12, take the day before the race off completely, and ignore the urge to test your fitness with one last hard session.
- Prepare everything two days before. Lay out your kit, attach your race number, charge your watch, check your shoes and pack the gels or sweets you practised with on long runs.
- Eat familiar, carbohydrate-rich meals. Normal portions of foods you know suit you, a little extra carbohydrate in the final two days, and nothing new, exotic or very rich.
- Plan the morning precisely. Set your alarm, know your breakfast and its timing, check transport and bag-drop arrangements, and arrive with time to spare rather than rushing to the start pens.
- Start slower than feels right. The first three miles should feel controlled, almost too easy. Race-day excitement and fresh tapered legs make the opening miles deceptive for almost every runner.
- Aim for a negative split. Run the second half slightly faster than the first: settle in the middle miles, then lift the effort gradually from mile 10 if you still feel strong.
- Fuel to your practised plan. Take your fuel at the times you rehearsed in training, drink to thirst at stations, and do not change anything because another runner is doing it differently.
- Finish, refuel and enjoy it. Walk, drink and eat within the hour, get warm and dry, and note how the race went while it is fresh — it is gold dust for whatever you plan next.
Pacing deserves one last emphasis, because it decides more half marathon results than fitness does. A negative split — a second half run slightly faster than the first — protects your fuel stores early and keeps you passing runners late on rather than being passed. Even pacing with a small lift at the end achieves the same thing; what matters is never banking time in the first half.
Disclaimer: this article is general fitness information only. It is not medical advice and does not replace guidance from your GP, a physiotherapist or a qualified coach who knows your history. Stop and seek advice if you feel unwell, dizzy or in pain while training.
What is a half marathon training plan?
A half marathon training plan is a structured schedule, usually around twelve weeks long, that builds your long run gradually towards 10 to 11 miles. It mixes mostly easy running with one weekly quality session of intervals or tempo work and finishes with a taper in the final week, so you can cover 13.1 miles, or 21.1 kilometres, confidently on race day.
How fit do I need to be before starting a half marathon training plan?
This twelve-week plan assumes you can already run a 5k comfortably, have completed a 10k or can run for around 40 to 50 minutes without stopping, and have been running two or three times a week for at least a month. If you are new to exercise, build that base first, and see your GP before starting if you have any health condition or concerns.
How long should my longest run be in half marathon training?
In this plan the long run builds in small steps from 5 miles in week 1 to a peak of 10 to 11 miles in weeks 10 and 11, before the taper in week 12. You do not need to run the full 13.1 miles in training: consistent weekly mileage plus a long run close to race distance prepares you fully, and race day itself carries you through the final miles.
What does a typical week look like on a half marathon training plan?
Most weeks contain four runs: two or three easy runs at a conversational pace, one quality session of intervals or tempo running, and one long run, with at least one full rest day and optional gentle cross-training such as cycling, swimming or walking. Add two short strength sessions of fifteen to twenty minutes each week, and never place the quality session and the long run on consecutive days.
What should I eat and drink on long runs?
Eat a normal carbohydrate-based meal two to three hours before a long run, such as porridge, toast or a bagel. On runs over about 90 minutes, take on carbohydrate little and often during the run, using gels, chews or jelly sweets you have practised with, and drink to thirst. Afterwards, eat a meal combining carbohydrate and protein within a couple of hours, and never try a new gel or breakfast on race day.
What are the injury warning signs in half marathon training?
Stop and rest if you have sharp or localised pain in one spot, pain that changes how you run, swelling or numbness, or pain that worsens week by week despite easier running. General tiredness and mild soreness that eases within a day or two are normal. If pain persists for more than a week, or you feel unwell, dizzy or have chest pain, see your GP or a physiotherapist.
Conclusion: Twelve Weeks to Your Spring Half Marathon
A good half marathon training plan is patient rather than complicated: mostly easy running, one quality session a week, a long run that grows from 5 miles to a peak of 10 to 11 miles, strength work twice a week, practised fuelling and a proper taper in week 12. Add honest attention to injury warning signs and sensible kit for dark winter evenings, and a spring half marathon becomes a realistic, enjoyable goal for an ordinary runner with an ordinary busy life.
Start now: check your base honestly, put week one’s four runs in your diary, and begin your half marathon training plan with one easy run this week. Twelve weeks from now you could be crossing a finish line in spring sunshine, medal in hand, wondering why 13.1 miles ever sounded daunting — and already thinking about what comes next.
