Quick Answer
A half marathon is 21.0975 km (officially), usually rounded to 21.1 km. It is exactly half a marathon. Average finish times range from around 2:00–2:10 for men and 2:15–2:25 for women across all levels. Beginners typically finish between 2:15 and 2:45, while experienced runners target under 1:45.
The Official Half Marathon Distance
The half marathon distance is fixed at 21.0975 kilometres (or 13.1094 miles). In everyday running conversations it is almost always rounded to 21.1 km. The official measurement is more precise because it matters for race certification, records, and course verification.
The half marathon sits exactly halfway between a 10 km race and a full marathon (42.195 km). That positioning is part of what makes it so popular — it demands genuine endurance and preparation, but it does not require the extreme training load of a full marathon. For many runners, it is the natural next step after completing a 10K.
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| Race Distance | Kilometres | Miles |
|---|---|---|
| 5K | 5.0 km | 3.1 miles |
| 10K | 10.0 km | 6.2 miles |
| Half Marathon | 21.1 km | 13.1 miles |
| Marathon | 42.2 km | 26.2 miles |
How Long Does It Take to Run a Half Marathon?
Finish times vary widely depending on your experience, training, age, and how you pace yourself on the day. The table below gives realistic targets across different runner levels.
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| Runner Level | Finish Time | Pace per km | Description |
|---|---|---|---|
| Elite | Under 1:05 | Under 3:05/km | Competitive racing athlete |
| Advanced | 1:20–1:35 | 3:48–4:31/km | Serious club or competitive runner |
| Experienced | 1:35–1:55 | 4:31–5:27/km | Regular runner, multiple races completed |
| Intermediate | 1:55–2:15 | 5:27–6:24/km | Running consistently for 6–12+ months |
| Beginner | 2:15–2:45 | 6:24–7:49/km | First or second half marathon |
| Run/Walk | 2:45–3:30+ | 7:49–9:55+/km | Finishing is the goal |
The most common goal for first-time half marathon runners is to finish under 2:30. A more aspirational target, often used as a milestone by recreational runners, is breaking 2:00 — which requires holding a pace of 5:41/km for the full 21.1 km.
Average Half Marathon Times by Age and Gender
Research from RunRepeat, analysing over 21 million race results, gives us reliable average times by demographic. Times naturally increase with age, particularly after 50, though older runners often pace more evenly and run more consistently than younger competitors.
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| Age Group | Men (Average) | Women (Average) | Pace/km (Men) | Pace/km (Women) |
|---|---|---|---|---|
| 18–29 | 1:57 | 2:14 | 5:32/km | 6:21/km |
| 30–39 | 1:55 | 2:13 | 5:27/km | 6:18/km |
| 40–49 | 1:58 | 2:16 | 5:35/km | 6:26/km |
| 50–59 | 2:06 | 2:26 | 5:58/km | 6:54/km |
| 60–69 | 2:21 | 2:44 | 6:41/km | 7:46/km |
| 70+ | 2:41 | 3:04 | 7:38/km | 8:43/km |
Runners in their 30s consistently record the fastest average times across both genders, though performance differences between the 18–29 and 30–39 groups are usually small. What matters far more than age is training history and consistency.
Half Marathon Finish Time Pace Chart
If you have a goal finish time in mind, use this chart to find the pace per kilometre you will need to maintain. Knowing your required pace before race day is one of the most important steps in pacing strategy — going out too fast in the first 5 km is the most common reason runners blow up in the final stretch.
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| Goal Time | Pace per km | Speed (km/h) | Level |
|---|---|---|---|
| 1:30 | 4:16/km | 14.1 km/h | Advanced |
| 1:45 | 4:59/km | 12.0 km/h | Experienced |
| 2:00 | 5:41/km | 10.6 km/h | Intermediate |
| 2:15 | 6:24/km | 9.4 km/h | Beginner–Intermediate |
| 2:30 | 7:06/km | 8.5 km/h | Beginner |
| 2:45 | 7:49/km | 7.7 km/h | Beginner/Run-Walk |
| 3:00 | 8:31/km | 7.0 km/h | Run-Walk |
To find the exact pace for your goal time or to convert between pace, speed, and finish time, use our running pace calculator.
How a Half Marathon Course Is Measured
When you line up at an official race, the 21.1 km distance has been independently verified — not guessed or mapped using a running watch. Official race courses are measured using a calibrated bicycle fitted with a mechanical counter, following the shortest possible legal racing line around corners and bends. This process is overseen by national athletics federations and must meet World Athletics standards.
Course organisers also add a small safety margin so that the course is never under distance. This means an official half marathon will always be at least 21.0975 km — it may be a few metres longer, but it will never be short.
What to do
If your GPS shows 21.3 or 21.4 km at the finish line, your watch is not wrong — it is simply recording every small deviation from the racing line, plus signal drift from buildings and trees. The course itself is accurate. Do not adjust your race pace targets based on GPS distance during the event; use time checkpoints at each kilometre marker instead.
Why Your GPS Watch Will Show More Than 21.1 km
This surprises almost every runner after their first race. GPS watches estimate distance by tracking your position through satellite signals, then connecting those data points to calculate how far you have moved. Each individual data point carries a small margin of error. Over 21 km, those small errors add up. Tight corners, tall buildings, tree cover, and weaving through a crowded start can all push the reading higher.
A reading of 21.2–21.4 km on a certified course is completely normal. Some runners at major city events report readings as high as 21.6 km due to the narrow streets and dense buildings. This is a GPS limitation, not a problem with the course. Your finishing time is what matters, and that is measured from the moment you cross the start mat to the moment you cross the finish mat — regardless of what your watch says about distance.
How Long to Train for a Half Marathon
The right training timeline depends almost entirely on where you are starting from. Running a half marathon does not require exceptional talent, but it does require consistent preparation. Trying to rush the distance with too little base fitness is one of the leading causes of injury and DNS (did not start) entries.
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| Starting Point | Training Time Needed | Recommended Plan |
|---|---|---|
| No running base (complete beginner) | 5–6 months | Couch to 5K first, then build to HM |
| Running 3–5 km comfortably | 16–20 weeks | Beginner half marathon plan |
| Running 5–10 km regularly | 10–14 weeks | Standard 12-week HM plan |
| Completed a 10K race | 8–12 weeks | Intermediate plan |
| Previous half marathon experience | 6–10 weeks | Goal-pace focused plan |
If you are starting from scratch, the best approach is to build a running base first using a Couch to 5K program, then transition into a structured half marathon training plan. Our 16-week half marathon training plan is designed to take runners from a solid 5 km base through to race-ready fitness.
Common Half Marathon Goals and What They Require
Most runners have one of three goals when they enter a half marathon: finish the race, break 2 hours, or run a personal best. Each requires a different approach to training and pacing.
Goal: Finish the race
Focus on time on feet rather than pace. Your long runs in training should build to at least 18 km. You do not need to run the whole way — combining running and walking is a valid strategy and one that many first-timers use successfully. To understand what untrained runners actually experience, see our guide on running a half marathon without training.
Goal: Break 2 hours
You need to hold 5:41/km for the full 21.1 km. This is an achievable target for runners who have been training consistently for 6–12 months. Our sub-2-hour half marathon guide covers exactly what training, pacing, and race day strategy this goal requires.
Goal: Break 1:45
A 1:45 finish requires holding 4:59/km — a more demanding pace that calls for structured speed work and a weekly mileage base of 40–50 km. See our detailed breakdown of how to run a 1:45 half marathon.
What the Half Marathon Feels Like at Different Points
Knowing what to expect during the race itself helps you pace correctly and make good decisions on the day. The half marathon is long enough that it cannot be run on willpower alone — pacing and fuelling matter throughout.
Kilometres 1–5: The temptation is to go out too fast. Adrenaline and crowd energy push most runners faster than planned. Force yourself to run at or slightly slower than your goal pace. If you feel too comfortable, you are probably pacing correctly.
Kilometres 6–10: This is typically the most comfortable section. Your body has warmed up fully, the early pack has spread out, and your pace should feel sustainable. Take your first gel or fuel around the 45-minute mark if using race nutrition.
Kilometres 11–15: Where the race begins in earnest. If you went out too fast, you will start to feel it here. Focus on maintaining form — a slight forward lean, relaxed shoulders, and a consistent cadence. Check your splits against goal pace rather than trying to accelerate.
Kilometres 16–21.1: The final stretch is where your training pays off. Runners who paced well in the first half often find they can run the second half faster than the first (a negative split). If you are struggling, shorten your stride and focus on turnover rather than stride length.
Is a Half Marathon the Right Distance for You?
The half marathon is widely considered one of the best race distances for recreational runners — challenging enough to require genuine preparation, but accessible to anyone willing to train consistently for a few months. Fewer than 1–2% of adults have ever completed a half marathon, which puts it well within the reach of most healthy adults while remaining a meaningful accomplishment.
If you have completed a 5K or 10K and are looking for the next step, a half marathon is the natural progression. If you are currently not running at all, start with a Couch to 5K program and give yourself 5–6 months to build the base you need. If you want to understand how many steps the distance involves, our guide to marathon and half marathon step counts breaks it down by pace and stride length.
Want a personalised half marathon plan?
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FAQ: How Long Is a Half Marathon
How long is a half marathon in km?
A half marathon is 21.0975 kilometres, rounded to 21.1 km in everyday use. It is exactly half the distance of a full marathon.
How long does it take to run a half marathon?
Most runners finish between 1:45 and 2:45 depending on experience and training. The average across all runners is roughly 2:05 for men and 2:20 for women. Beginners typically aim for 2:15–2:30 as a first-race target.
What is a good half marathon time for a beginner?
Any finish time is a great result for a beginner. Most first-timers target 2:15–2:45. If you can run the whole distance at a pace where you could hold a conversation, you are likely on track for around 2:20–2:30.
Why does my GPS show more than 21.1 km after a half marathon?
GPS watches accumulate small positioning errors over time, especially around corners, in crowds, and near buildings. A reading of 21.2–21.4 km on a certified course is normal. The course itself is accurately measured and the finish time recorded by the official chip is what counts.
How long does it take to train for a half marathon?
Runners with no base need around 5–6 months. Those already running 5–10 km comfortably can typically prepare in 10–14 weeks. A structured plan with 3–4 running sessions per week and a weekly long run is the most reliable path to the start line.
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