A marathon is 26.2 miles — precisely 26 miles and 385 yards, which is 42.195 kilometres. That is not an approximation that varies by race: it is the fixed official distance for every certified marathon in the world, standardised in 1921 and still the figure in World Athletics’ marathon page today. A half marathon is exactly half of it: 13.1 miles, or 21.0975 kilometres. The odd precision of the number — why 385 extra yards, why not a round 26 miles or 42 kilometres — is a historical accident involving a royal nursery at Windsor Castle, and it is explained below, along with the question people usually ask next: how long those 26.2 miles actually take.
The distances at a glance:
| Race | Miles | Kilometres | Exact imperial form |
|---|---|---|---|
| Marathon | 26.2 (26.2188) | 42.195 km | 26 miles 385 yards |
| Half marathon | 13.1 (13.1094) | 21.0975 km | 13 miles 192.5 yards |
| 10K | 6.2 | 10 km | — |
| 5K | 3.1 | 5 km | — |
The official distance, and what “official” means
The marathon’s 42.195 kilometres is set by World Athletics, the sport’s world governing body (known until 2019 as the IAAF). Its discipline page for the marathon states the standardised distance directly: 26 miles 385 yards (42.195km), standardised in 1921. The figure is written into the World Athletics Competition and Technical Rules, whose road-race provisions govern how courses are measured and certified.
That certification is why your local marathon and the Olympic marathon are the same length. A course that wants its results to count — for records, qualifying times, rankings or championship entry — must hold a valid international course measurement certificate, as World Athletics’ certified road events page sets out: performances are only eligible when they are achieved at a competition run under World Athletics rules on a properly measured course. Courses are measured along the shortest possible route a runner can take, with a small safeguard built in so a measured course cannot come up short — which is also why, as explained below, your own watch will almost always say you ran a little further than 26.2 miles.
Two clarifications the headline figure hides. First, 26.2 is a rounding: the true figure is 26.2188 miles, and the 0.0188 beyond the round number is the famous 385 yards (about 352 metres). At a steady 10 minutes per mile, those 385 yards alone take about 2 minutes 11 seconds — a small eternity at mile 26. Second, the distance applies to road marathons. Races calling themselves trail marathons follow their own courses over terrain and can measure slightly long or short; if the exact distance matters to you, check whether the event holds a course measurement certificate.
Why 26.2 miles? Windsor Castle, a royal box, and 1921
The marathon is named after the legendary run of a Greek soldier — Philippides, also given as Pheidippides — from the battlefield of Marathon to Athens to announce the defeat of the invading Persians. As World Athletics tells it, the organisers of the first modern Olympic Games, at Athens in 1896, devised the marathon race over 40 kilometres to celebrate the achievements of ancient Greece. For the first decades of the modern Games there was no fixed marathon distance at all: each host city laid out a course of roughly that length, and the actual distance changed from Games to Games.
The number we still use was created at the 1908 Olympic Games in London. The course ran from Windsor Castle to the White City Stadium in west London. World Athletics’ account of the change is specific: the distance was extended to the imperial measurement of 26 miles at those Games, “and increased another 385 yards when the starting line was pulled back so it could be seen by the children in the Royal Nursery at Windsor and still finish in front of Queen Alexandra at the White City Stadium.” So the two ends of the course were both set by royal sightlines — a start the royal children could watch from the nursery, and a finish directly in front of the Queen in the stadium — and the road between them, plus the partial lap of the track at the end, happened to total 26 miles and 385 yards.
That might have remained one Games’ quirk. What made it permanent came thirteen years later: in 1921 the international federation — the IAAF, now World Athletics — standardised the marathon at 26 miles 385 yards (42.195 km), taking the 1908 London distance as the template. It has not changed since. Every “26.2” sticker, tattoo and finisher’s medal is, in effect, quoting the distance between a nursery window at Windsor and a royal box in a demolished London stadium.
The women’s Olympic marathon arrived much later — the first one was held at the 1984 Los Angeles Games, a fact worth pausing on: the distance had been fixed for men for over sixty years before women were allowed to race it at the Olympics.
The half marathon: exactly half, and not an afterthought
A half marathon is 21.0975 kilometres, or 13.1 miles — exactly half the marathon distance, not a separate historical course. That exactness matters for comparisons: a half marathon time is directly half the distance, so doubling a half time gives a rough marathon equivalent before fatigue is accounted for (in practice, almost nobody doubles their half time exactly; the second half of a marathon costs more than the first).
The half has grown into the more popular distance of the two in many countries precisely because it is a serious endurance test — two hours or so for a typical finisher, at the same roughly 10-minute-mile pace that puts the median full-marathon finisher at about 4:26 — that does not demand the marathon’s training volume or recovery. It is also the standard stepping stone: most marathon training plans and most first-time marathoners pass through a raced half on the way to the full distance, using it to practise pacing, drinking on the move and finishing strongly, all at exactly half the cost in distance. The same certification logic applies: a half marathon whose results are to count must be measured to its full 21.0975 kilometres. If you are comparing distances across sports rather than within running, the “how long” question changes shape entirely — a football match’s length, for instance, is set by a clock rather than a course, as how long is a soccer game explains.
How long does a marathon take? Time, not distance
“How long is a marathon” also means time, and here there is no official number — only a distance and the pace you cover it at. The honest way to answer is with the arithmetic, because any “average” hides an enormous spread between the front of the field and the back.
Work it out from pace, over the exact 26.2188 miles:
| Pace per mile | Pace per km | Finish time |
|---|---|---|
| 8:00 | 4:58 | about 3:30 |
| 9:00 | 5:36 | about 3:56 |
| 10:00 | 6:13 | about 4:22 |
| 10:30 | 6:31 | about 4:35 |
| 11:00 | 6:50 | about 4:48 |
| 12:00 | 7:27 | about 5:15 |
| 15:00 (brisk walking) | 9:19 | about 6:33 |
Read the table from the middle out. Large analyses of race results — tens of millions of finish times — put the median finisher at roughly 4 hours 26 minutes, which is a pace of about 10:06 to 10:10 per mile held for the full distance: in other words, the runner exactly in the middle of the field is running a little over 10-minute miles. Men cluster somewhat faster and women somewhat slower in those analyses (medians around 4:14 and 4:42 respectively), and the average has drifted slower over the decades as the field has broadened from a small group of trained racers to mass-participation events where finishing is the goal. Treat any single “average marathon time” you see quoted without a dataset behind it with suspicion — figures between about 4:20 and 4:40 can all be defended depending on which races, years and countries are counted, which is why the pace table above is the more useful tool: find the pace you can realistically hold, and the finish time follows.
At the extremes: elite men race at close to 4:35 per mile and elite women at close to 5:00 per mile, finishing in the region of two hours to two hours and ten minutes. At the other end, most big-city marathons keep their courses open for roughly six to seven hours, which is a 14-to-16-minute-per-mile pace — a determined walk-run. A first marathon anywhere between 4 and 5 hours is squarely in the middle of what trained recreational runners actually do, and finishing at all puts a runner ahead of everyone who never started: the field those medians describe consists only of people who trained for months and completed 26.2 miles.
One warning about your own data: your GPS watch will very likely congratulate you on running 26.4 or 26.5 miles. That does not mean the course was long. The course was measured on the shortest possible line through every corner; you, weaving between runners, drifting wide on bends and stopping at drink stations off that line, ran further than the measured route — and GPS signal error adds a little more. The certified distance is the 26.2; the extra is yours.
Frequently asked questions
How many miles is a marathon, exactly? 26.2 miles as usually quoted; exactly 26 miles 385 yards, which is 26.2188 miles, or 42.195 kilometres. The distance was standardised in 1921 and is the same for every certified marathon worldwide.
How many kilometres is a marathon? 42.195 kilometres — 42,195 metres. The metric figure is the official one written into World Athletics’ rules; the mile figure is its imperial equivalent.
How many miles is a half marathon? 13.1 miles (13.1094 exactly), or 21.0975 kilometres — exactly half the marathon distance.
Why is a marathon not exactly 26 miles? Because the 1908 London Olympic course it copies was stretched by 385 yards so the start could be seen from the Royal Nursery at Windsor Castle while the finish stayed in front of Queen Alexandra at the White City Stadium. When the distance was standardised in 1921, that exact course length was adopted rather than a round number.
How long does a half marathon take a typical runner? About two hours or so. The distance is exactly half, so the pace table works the same way: at 10 minutes per mile, 13.1 miles takes about 2 hours 11 minutes, and doubling a half time only roughly predicts a marathon time, because the second half of a full marathon costs more than the first.
How long does it take a typical runner to finish a marathon? The median finisher in large race-result analyses takes about 4 hours 26 minutes — roughly 10-minute-mile pace. Trained recreational runners mostly finish between about 3:30 and 5:30; elites finish in just over 2 hours; course time limits are commonly around 6 to 7 hours. If you are counting heads rather than miles, how many players are on a basketball team is the neighbouring “how many” question in this section.
This article is general information, based on World Athletics’ marathon page, certified road-events criteria and Competition and Technical Rules linked above, checked in November 2026. Finish-time figures are pace arithmetic over the official distance plus the median reported by large published analyses of race results, as described in the article; individual races set their own entry standards and course time limits.