How long does it take to train for a half marathon?
It depends on where you start. The half marathon is 21.1 km, and most plans assume you can already run about 5 km without stopping. From there, 9 to 12 weeks is enough for most people to finish comfortably. If you are starting from scratch, build a running base first: rushing the long run is the most common cause of injury in first-time half marathoners.
| Your starting point | Recommended plan length | Focus |
|---|---|---|
| Not running yet | 16–20 weeks | Start with a run/walk plan until you can run 30 minutes, then a 5K, then the half marathon plan |
| Can run 5 km continuously | 10–12 weeks | Gradually extend the long run; keep most runs easy |
| Run 10 km regularly | 8–10 weeks | Long run up to 18–20 km plus one tempo session a week |
| Experienced, chasing a personal best | 12 weeks | Threshold and interval work, race-pace long runs |
What a half marathon training week looks like
Every good plan is built from the same few ingredients: mostly easy running, one long run, one or two harder sessions, rest, and strength work. What changes between levels is the volume and how much of it is fast.
| Level | Runs / week | Weekly distance (peak) | Quality sessions | Peak long run |
|---|---|---|---|---|
| Beginner | 3–4 | 25–35 km | Strides or a short tempo | 16–18 km |
| Intermediate | 4–5 | 35–50 km | 1 (tempo or intervals) | 18–20 km |
| Advanced | 5–6 | 50–70 km | 2 (threshold + intervals) | 20–24 km with race-pace segments |
- Easy runs: at a conversational pace. Roughly 80% of your weekly running should feel easy, even if it feels too slow.
- Long run: once a week, growing by 1–2 km at a time, with an easier "cutback" week every third or fourth week.
- Tempo run: 15–30 minutes at a comfortably hard effort, about the pace you could hold for an hour.
- Intervals: for example 5–6 × 1 km at around 10K pace with 2 minutes of easy jogging between.
- Strength: two short sessions a week (squats, lunges, step-ups, calf raises, planks). Strong legs and core are what get you through the last 5 km.
- Rest: at least one full rest day a week. Adaptation happens during recovery.
Half marathon pace chart
Use this chart to turn a goal time into a per-kilometre pace and checkpoint splits. Pick a goal from a recent race or time trial rather than a hopeful guess: a 10K time multiplied by about 2.2 is a reasonable starting estimate for a half marathon.
| Goal time | Pace per km | 5 km split | 10 km split | 15 km split |
|---|---|---|---|---|
| 1 h 30 min | 4:16 /km | 21:20 | 42:40 | 1:03:59 |
| 1 h 45 min | 4:59 /km | 24:53 | 49:46 | 1:14:39 |
| 2 h | 5:41 /km | 28:26 | 56:53 | 1:25:19 |
| 2 h 15 min | 6:24 /km | 32:00 | 1:03:59 | 1:35:59 |
| 2 h 30 min | 7:07 /km | 35:33 | 1:11:06 | 1:46:39 |
| 2 h 45 min | 7:49 /km | 39:06 | 1:18:12 | 1:57:19 |
| 3 h | 8:32 /km | 42:40 | 1:25:19 | 2:07:59 |
Training for half marathons in Indian conditions
Most Indian road races are held between October and February, when it is cooler, which means most training happens through the monsoon and the start of winter. Plan for three conditions:
- Heat and humidity: run early (before 7 am in most cities), slow your pace on humid days and judge effort by breathing or heart rate rather than the watch. Coastal races such as Mumbai stay humid even in January.
- Air quality: check the AQI before hard sessions, especially in North India from November to January. On days rated "Poor" (201–300) or worse on the CPCB scale, move intervals indoors or onto a treadmill, or swap them for an easy session.
- Monsoon: wet roads and trails need shoes with grip, anti-chafe balm and visible clothing. Swap a waterlogged long run for a treadmill or covered-track session rather than skipping it.
Fuelling and hydration
Most runners finish a half marathon in 1.5 to 3 hours, long enough for fuelling and fluids to matter. Practise your plan on long runs so race day holds no surprises.
- Carbohydrate: around 30–60 g per hour once you are past about an hour of running, for example a gel every 30–45 minutes. Many runners under 1:45 need little or nothing during the race.
- Fluids: drink to thirst and aim to avoid losing more than about 2% of body weight. In hot, humid conditions that can mean roughly 400–800 ml per hour; weigh yourself before and after a long run to learn your sweat rate.
- Electrolytes: in humidity you lose a lot of sodium through sweat. An electrolyte drink or tablet helps on runs over an hour.
- Race morning: eat a familiar, carbohydrate-based breakfast 2–3 hours before the start, such as poha, idli, toast with banana or oats.
- Nothing new on race day: no new shoes, gels or breakfast.
Taper and race week
Cut your training volume by roughly 30–50% over the final 7–10 days while keeping a few short race-pace efforts so your legs stay sharp. Sleep more, keep meals familiar and lay out your kit the night before.
On race day, start slower than goal pace for the first 2–3 km. Most runners who struggle in the second half started too fast, often carried along by the crowd at the start.
Common half marathon training mistakes
- Increasing weekly distance too quickly. A common rule of thumb is no more than about 10% a week.
- Running every session too fast, which leaves you tired for the runs that matter.
- Skipping strength training and mobility.
- Ignoring pain that changes how you run. Rest for 2–3 days, and see a physiotherapist if it persists.
- Not practising fuelling and hydration on long runs.
This guide gives general training information, not medical advice. If you have a heart condition, high blood pressure, an injury or have not exercised for a long time, check with a doctor before starting a training plan.