What Is a Half Marathon?
A half marathon is 13.1 miles, or 21.0975 kilometers, which is exactly half the length of a full marathon. The distance has grown into the most popular road race in many countries because it asks for real endurance without the months of heavy mileage a marathon demands. A fit recreational runner can prepare for one in two to three months, and the effort on race day lasts long enough to test pacing and fueling while staying within reach of a first-timer who has built a steady base.
The race format matches longer road events, with runners covering a measured course on roads usually closed to traffic and moving through aid stations stocked with water and sports drink. Finish times spread widely: strong amateurs come through near 90 minutes, mid-pack runners finish between two and two and a half hours, and the fastest professionals run far quicker. The men’s record stands at 57:20 and the women’s at 1:02:52, paces that hold close to three minutes per kilometer for over an hour.
How It Compares to Other Distances
The half marathon sits at a useful middle ground, long enough that fitness, pacing judgment, and in-race fueling all matter, yet short enough that recovery takes days rather than weeks. Many runners treat it as preparation for the full marathon, since the training overlaps and a half marathon result gives a reliable read on marathon-day pace. Others treat it as their main event and chase faster times year after year without ever moving up to 26.2 miles.
Pacing usually decides the race, because the distance is short enough to tempt a fast start and long enough to punish one. The second half, especially the final 5 kilometers, is where a runner who went out too hard loses the most time. A measured first 10 kilometers followed by a steady or slightly faster close produces the best results for most people.
Training for the Distance
A half marathon plan centers on a weekly long run that climbs toward 10 to 12 miles, supported by easy runs through the week and one faster session such as a tempo run or intervals. Total weekly mileage rises gradually, and a short taper in the final week sharpens the legs for race day. Runners coming from a 5K or 10K background usually adapt well, since they already hold the speed and only need to extend their endurance.
The race is also a common target for runners building toward longer goals. Because the training base transfers directly, a half marathon often appears partway through a marathon block as a tune-up race, giving the runner a real-world check on fitness and pacing under race conditions.
Fueling the Race
Carbohydrate matters at this distance, though less than in a marathon. Most runners hold enough stored glycogen to cover 13.1 miles, but topping up keeps pace from fading in the closing miles, particularly for anyone running longer than 90 minutes. A useful approach is to take in carbohydrate during the race at a modest rate, often one or two energy gels spaced through the second half, along with sips of sports drink at the aid stations. Faster runners may need only a single gel, while those out on the course for two hours or more benefit from a steadier intake.
Hydration and sodium also play a role, especially in heat, since sweat removes electrolytes from the body and on a warm day a runner who drinks only plain water can dilute their sodium and lose performance or feel unwell. Practicing both drinking and fueling on long training runs lets the gut adjust before it matters.
Reading a Half Marathon Result
The same timing rules apply as in any large road race. Chip time, measured from the moment a runner crosses the start mat, is the number that counts for personal records, while gun time runs from the official start of the race. A negative split, running the second half faster than the first, is the mark of good pacing and steady fueling. For many runners the half marathon becomes a yearly benchmark, a distance they return to in order to measure fitness, since the effort is demanding enough to be honest and accessible enough to repeat without a long recovery.
A Distance That Keeps Growing
The half marathon has spread faster than any other road distance, and the reasons are practical. The training fits around a working life, the entry cost and travel are lower than a destination marathon, and the recovery lets a runner race several times a year. Race organizers have answered that demand with large, well-supported events in nearly every major city, many of them paced and chip-timed to the same standard as a full marathon. For a runner deciding how far to commit, the half offers a serious goal that does not take over the calendar.
Genuine endurance, a manageable training load, and a clean tie to the marathon explain its rise, and runners now have more half marathons to choose from than any other distance on the calendar.