How to choose your first marathon

Your first marathon is the one race where the course and the conditions matter more than the medal or the city. A flat route, a cool morning and a field big enough to run with can be the difference between a good day and a long walk to the finish. Here is what to look at, in order of how much it changes your day.

1. Give yourself enough time to train

Most first-marathon plans run 16 to 20 weeks, on top of a few months of regular running. Count back from race day before you commit: a race four months away is tight if you are building up from short runs. Autumn and spring are the busiest seasons, so there is plenty of choice for a date that fits your plan.

2. Pick a flat course

Climbing costs time and, more importantly, energy you will want in the last 10 km. For a first marathon, look for a total climb under about 150 m. Every race page on iRun42 shows the elevation gain and the course profile, and the flattest marathons list ranks them worldwide. Watch out for courses that are “flat” overall but finish with a long climb.

3. Aim for a cool start

Most runners race best when it is cool at the start, roughly 5 to 12°C, and heat hurts a first-timer more than anyone, because you are out on the course for longer and the day warms up while you run. Each race page shows the usual start temperature and how warm it gets during the race, from ten years of weather data. The best marathon weather guide shows which months are coolest, and the cool-weather marathons list puts them in order.

4. Check the cut-off

Many marathons close the course after six hours, some after five, a few after seven or more. Take your expected time from a recent half marathon (the race time calculator adjusts it for the course’s hills and heat), add a margin for a bad day, and make sure you finish well inside the limit. Where an organiser publishes a time limit, it is on the race page.

5. Choose a big, well-supported race

A large field means people around you at your pace all the way, more aid stations, pacers and crowds along the course. Races with a few thousand finishers or more are usually the easiest to run a first marathon in. Some of the biggest need a lottery, though, which brings us to entry.

6. Make sure you can get in

If you have your heart set on a race, check how entry works before you plan around it. Lottery races can leave you without a place months into your plans (see marathon lotteries explained). For a first marathon, an open-entry race where you simply register is the safer choice: the big marathons without a lottery are a good start.

7. Keep the travel simple

A race close to home means your own bed, food you know and no jet lag. If you travel, a short flight and a small time difference make the last days easier; arrive at least two days before the race. Race pages show the flight time and time difference from your home airport, and our race trip guide has a booking timeline.

A shortlist: the friendliest first marathons

These open-entry road marathons are flat (250 m of climbing or less), usually start between 4 and 16°C, have at least 2,000 finishers and, where published, a cut-off of six hours or more. The list updates with our race data.

See the full ranking in the best marathons for your first marathon, or browse by country and month, for example marathons in Europe or marathons in North America.

Not ready for 42.2 km yet?

A half marathon a couple of months before your marathon is a great rehearsal for pacing, fuelling and race-morning routine, and it gives you a time to predict your marathon from. The flattest half marathons are a good place to look.