How long is a marathon?

The distance is fixed; the time is not. The middle of the field finishes in about 4 hours 30 minutes: Runsy's synthesis of four published studies covering more than 100 million race results, not a rule of thumb. That is 4:30 marathon pace: 10:18 per mile. The table below turns any target finish into the pace it demands and the splits you would have to hit to hold it.

Here is the part a distance page normally leaves out. The race distance is not the number that governs your training: your weekly volume is, and the race distance mostly sets a floor under it.

So rather than describe that in the abstract, here is what Runsy's plan engine actually generates for a beginner with sixteen weeks: three runs a week, no doubles, no track sessions, no cross-training you have to schedule. In the app, the same kind of plan is built from the runs you have actually done (Runsy pricing).

The longest run in that plan is 29 km: thirteen kilometres short of the race, and that is deliberate rather than an oversight. It is the standard shape of marathon training at every level, from first-timers to people chasing a qualifying time.

The reasoning is a trade. A 29 km run at genuine easy pace already takes three hours and change, and beyond roughly that point the recovery cost of going further climbs faster than the fitness you get back: you spend the following week too tired to do the training that was supposed to make you faster. Runsy's engine caps the long run where that trade turns, which is the same rule most published plans arrive at. The 20-week version climbs to the same 29 km in smaller steps.

The last thirteen kilometres on race day are bought with the other 591 in the block, with the taper, and with fuelling, not with one heroic Sunday.

591 km at a genuine easy pace of 6:30 to 7:00 per kilometre is somewhere between 64 and 69 hours of running, spread across four months. That averages a little under four and a half hours a week: less than most people fear and more than most people have spare. For the energy side of those hours, the calories burned running calculator puts a number on it.

It is not evenly distributed, which is the part worth planning around. Weeks 1 to 3 run 29 to 35 km and fit inside an ordinary life. Weeks 9 to 12 are the pinch: 47 to 52 km each, with a long run of 26 to 29 km that will take most of a weekend morning, every weekend, four weeks running. If there is a fortnight in your calendar that cannot absorb that, put it in weeks 4, 8, or the taper.

If sixteen weeks does not fit, the same engine builds a 20-week version that reaches the same 52 km peak more gradually, and a 12-week version for runners who already have a base. Start from the marathon plans index if you are not sure which level you are.

The first modern Olympic marathon, Athens 1896, was run over about 40 km: roughly the distance from Marathon to Athens, which is where the name comes from. The distance was not fixed at that point; early Games used whatever the course measured.

Then London, 1908. According to World Athletics, the course was set at 26 miles and then grew by another 385 yards when the start line was pulled back. The version usually told puts the finish in front of the royal box instead. Either way the race came to 26 miles and 385 yards, 42.195 km, and that was standardised as the marathon distance in 1921.

So the answer to "why 26.2 and not 26?" is that one Olympic course in 1908 happened to be 385 yards longer than 26 miles, and the sport standardised on it thirteen years later. Nothing about the human body chose it.

The half marathon is exactly half, which makes it the only honest checkpoint on the way, and the reason most marathon blocks put a half-marathon race somewhere in the build. Doubling a half-marathon time and adding ten to twenty minutes is the crude version of a marathon prediction, and it is crude for a real reason: the second half is run on a body that has already used most of its stored carbohydrate.

If you have never raced a marathon, a half-marathon block first is not a detour. It is the fastest route.