How Long Is a Marathon? Distance, Measurement and Finish Times

A full marathon is 42.195 kilometres, which equals 26 miles and 385 yards (about 26.2 miles). A half marathon is exactly half that distance: 21.0975 kilometres, or roughly 13.1 miles. New Zealand events such as the Auckland and Queenstown marathons usually round these figures to 42.2 km and 21.1 km on their course maps, but every certified race must cover the full 42.195 km to count as an official marathon. This guide explains that distance in kilometres and miles, why the number is so oddly specific, how course organisers measure it, and how long it typically takes runners to finish.

The short answer: how long is a marathon?

The official marathon distance is 42.195 km. This has been the fixed, worldwide standard since 1921, when the International Association of Athletics Federations (IAAF, now known as World Athletics) adopted it as the single legal distance for the event. Any race marketed as a “marathon” that is measured and certified to this standard covers exactly 42.195 km — no more and no less — which is why times set on certified courses can be compared and ratified as records.

If you want a pure breakdown of the distance itself, our companion explainer on how far a marathon is covers the conversions in more detail. Below, the focus is on the length in context: distance, history, measurement and finish times.

Marathon distance in kilometres, miles and steps

The marathon distance is defined in metres, then converted to imperial units for countries that still use miles. Understanding both, plus a rough step count, helps you visualise the effort and plan your pacing.

Kilometres and miles

Across metric and imperial units, the full marathon works out to:

• Kilometres: 42.195 km (commonly rounded to 42.2 km)
• Miles: 26 miles and 385 yards, which is about 26.219 miles
• Metres: 42,195 metres

How many steps is a marathon?

Most runners take somewhere between roughly 50,000 and 55,000 steps to complete a marathon, depending on stride length and height. Shorter runners with quicker cadence sit at the higher end, while taller runners with a longer stride take fewer. On a standard 400 m athletics track, 42.195 km is just over 105 laps, which is why marathons are run on roads rather than tracks.

How the marathon compares to other race distances

The marathon sits near the top of the mainstream road-racing ladder, above the 5K, 10K and half marathon but below the ultramarathon. Anything longer than 42.195 km is classed as an ultra; you can read more about those in our guide to ultra marathon distances. The table below puts the common distances side by side.

Why is a marathon 42.195 km? The history behind the number

The marathon is 42.195 km because of a route change at the 1908 London Olympics, later locked in as the global standard in 1921. The distance was not always fixed, and the famous number is a relatively modern accident rather than an ancient measurement.

The Pheidippides legend

According to popular legend, a Greek messenger named Pheidippides ran from the battlefield at Marathon to Athens — a distance of about 40 km (roughly 25 miles) — to announce the Greek victory over the invading Persians, then collapsed and died from exhaustion. Historians treat the collapse-and-die version as a later, romanticised embellishment; the earliest account, from Herodotus, describes a much longer run from Athens to Sparta to request help before the battle. Even so, the Marathon-to-Athens story inspired the first modern Olympic marathon in Athens in 1896, which covered approximately 40 km.

From about 40 km to 42.195 km: the 1908 London compromise

The exact 42.195 km figure comes from the 1908 London Olympic Games. Organisers set the start on the lawn of Windsor Castle and the finish inside White City Stadium in front of the royal box, and the resulting route measured 26 miles and 385 yards. In the years before this, the Olympic marathon distance varied considerably — for example, about 40.2 km in Stockholm in 1912 and about 42.75 km in Antwerp in 1920.

Standardisation in 1921

The 1908 London measurement was formally adopted as the universal marathon distance by the IAAF in 1921. From the 1924 Paris Olympics onward, every Olympic marathon — and every course certified as a marathon — has used the 42.195 km standard, which is why the oddly specific number has stuck for more than a century.

How marathon courses are measured

Certified marathon courses are measured with a calibrated bicycle rather than a car odometer or GPS, because road racing demands accuracy far tighter than consumer devices provide. This is how organisers guarantee that a 42.195 km course really is 42.195 km.

The calibrated bicycle and Jones Counter method

The approved method attaches a mechanical revolution counter — the Jones Counter — to the front wheel of a bicycle. The measurer first calibrates the counter over a short course of known length that has been measured with a steel tape and corrected for the temperature of the road surface. The bicycle is then ridden along the shortest possible legal line of the race route (the racing tangents) several times, and the counted wheel revolutions are converted into distance. This method has measured nearly every Olympic marathon course since it was introduced.

The short course prevention factor

To make sure a course is never accidentally too short, measurers deliberately add a small margin called the short course prevention factor — one tenth of one percent — to the calibration. In practice this means a certified marathon is measured to be at least 42.195 km, and typically a handful of metres longer, so no record is ever disallowed for running on an under-length course. Overall measurement accuracy is usually better than one metre in a thousand.

Average marathon finish times and cut-offs

The average marathon finish time worldwide is roughly four and a half hours, not the six-to-seven-hour cut-off window that is sometimes quoted. Finish times vary widely with experience, age, sex and course profile, so it helps to separate the typical result from the elite and the time limit.

What is a typical marathon finish time?

Across hundreds of thousands of finishers, the global average sits at about 4 hours 30 minutes, with a 2024 median close to 4:25. Broken down by sex, men average around 4:14 and women around 4:41. First-time runners often target a finish somewhere between 4 and 5 hours, while elite athletes complete the full distance in a little over 2 hours. If you are chasing a specific goal, a marathon pace chart shows the exact per-kilometre pace each target time requires.

How long does it take to walk a marathon?

Walking a marathon typically takes between 6 and 8 hours, depending on your walking speed and fitness. A steady pace of about 6.5 km/h finishes in roughly 6.5 hours, but many events set a cut-off that walkers need to check before entering, because the course may close before slower participants finish.

Race-day cut-off times in New Zealand

Cut-off times are set by traffic management and road-closure rules, not by the average finisher. At the Auckland Marathon, for example, participants have around 7 hours to complete the full course, with staged checkpoint cut-offs along the way. At the Queenstown Marathon, the course officially closes at 4:00 pm, which gives roughly a 7.5-hour window from the morning start, again enforced through intermediate checkpoints. Always confirm the current year’s limits on the official event site before entering.

What affects your marathon time

Your finish time depends on a mix of preparation and race-day conditions. The main factors are:

• Training consistency: weekly mileage, long runs and tempo sessions build the aerobic endurance and muscular resilience the distance demands.
• Fuelling and hydration: steady carbohydrate intake and electrolytes help you avoid “hitting the wall” — the sudden energy crash caused by glycogen depletion in the later kilometres.
• Course elevation and terrain: hilly or trail courses are slower than flat, sealed roads.
• Weather: heat, humidity and strong headwinds all add cardiovascular strain and slow you down.
• Pacing discipline: starting too fast is the single most common reason runners fade in the second half.

Common mistakes runners make with the marathon distance

Most marathon disappointments come from a handful of avoidable errors rather than a lack of fitness. Watch for these:

• Underestimating the last 10 km: the second half is far harder than the first because fatigue does not scale evenly; a marathon is much more than “two half marathons”.
• Running more than the measured distance: courses are measured on the shortest legal line, so weaving between runners and taking wide turns can add several hundred metres to your personal total.
• Trusting GPS distance over the official markers: watches often read slightly long on a marathon because of signal drift and imperfect tangents, so pace to the course markers.
• Trying new fuel or shoes on race day: anything you have not practised in training is a gamble over 42.195 km.
• Ignoring the cut-off: slower runners and walkers should check checkpoint times in advance so they are not pulled from the course.

Is a marathon right for you, and how to start

A marathon suits runners who can already cover shorter distances comfortably and are willing to commit to a structured 16 to 20 week build-up. Complete beginners are usually better served by working up through a couch to 5K training plan and a half marathon first, then progressing to the full distance once a weekly long run of 30 km or more feels manageable. The distance itself never changes — 42.195 km — but the preparation is what turns it from daunting into achievable.

Frequently Asked Questions (FAQ)

How long is a marathon in kilometres?

A standard full marathon is exactly 42.195 kilometres, often rounded to 42.2 km on New Zealand course maps. A half marathon is 21.0975 kilometres, usually shown as 21.1 km.

How many miles is a marathon?

A marathon is 26 miles and 385 yards, which is about 26.219 miles and is commonly written as 26.2 miles. A half marathon is roughly 13.1 miles.

How long does it take to walk a marathon?

Walking a marathon usually takes between 6 and 8 hours, depending on your walking speed and fitness. Check the event’s cut-off time before entering, because the course may close before very slow participants can finish.

Is a marathon harder than a half marathon?

Yes. A half marathon is 21.1 km, but fatigue does not scale evenly, so the second half of a full marathon brings much greater glycogen depletion, muscle damage and mental strain, making the full distance considerably more demanding than two halves.

Why is a marathon 42.195 km and not a round number?

The exact figure comes from the 1908 London Olympics, where the route from Windsor Castle to the royal box inside White City Stadium measured 26 miles and 385 yards. The IAAF adopted this as the universal standard in 1921.