The Fastest and Slowest Ironman Races of 2025

The 2025 Ironman race season has come to a close. This year saw a total of 38 Ironman races, including the two world championship events. Just over 58,000 athletes raced Ironman this year, some more than once. Of those who started, roughly 53,500 crossed the finish line.

Now that the season is done, let’s take a look back at which events were the fastest, and which were the slowest in 2025.

2025 Ironman races at a glance

In total, the 38 Ironman events showed a small increase over 2024 with the addition of three new events – Leeds, Les Sables, and Ottawa – along with the return of Ironman Taiwan after a two-year hiatus. While we gained some new races, Ironman Canada and Philippines were no longer part of the season.

To rank races, I used the average age-group times from each event. Of course, not every race goes to plan: Ironman Australia had a canceled swim and ranked first thanks to this time savings. Taiwan’s swim was half the distance but still only ranked 29th fastest this year. I’ve excluded these two events to allow a fairer comparison of this season’s races.

The chart below plots these events by rank and time, from fastest on the left through to the slowest on the right. Races are color-coded based on their location. It’s quite easy to pick out that Europe is the hotspot for fast courses – nine of the top 10 are European races. North American and Australian/New Zealand races tend to rank somewhere in the middle of the bunch, while Asian races are among the slowest.

There’s a numbers game at play here, too, as around half of all Ironman races take place within Europe. Naturally, the continent dominates the chart.

Let’s take a closer look at the fastest and slowest events and how things stack up when we consider individual splits too.

Fastest Ironman races of 2025

The top five fastest races of 2025 consist of some of Europe’s fastest courses, along with South America’s fastest, Brazil. One of 2025’s new events, Ironman Les Sables, enters straight in at No. 2. Copenhagen maintains its position as the fastest age-group event from 2024.

Slowest Ironman races of 2025

At the other end of the scale, the five slowest events of 2025 are more than two hours slower on average than the fastest race of the year. We still have European races on the list, and the U.K. is still home to some of the slowest courses in the calendar. It was a tough year in Texas as it dropped down into the slowest five. Japan and Malaysia maintain their reputations for slow courses.

Fastest and slowest Ironman swim times of 2025

The swim is the shortest element of the race and, as such, has less bearing on how fast a race is. In the chart below, I plotted races’ overall ranking and their swim ranking against each other. It shows how scattered swim times are when compared with the final outcome. Some of the slowest races have top-10 swim times.

Ironman Les Sables is the only member of the fastest five races to also have a top-five swim time. It’s beaten by Chattanooga and California, both of which had exceptionally fast, downriver swim times. The world championship race in Nice makes a showing here – perhaps not surprisingly, given the need to qualify to compete there. Ironman Cozumel has seen a lot of variation in its times over the years, due to ocean currents; this year was a fast one in the water.

The Asian races dominate the slowest swims of 2025. Texas makes an appearance, but it’s Ironman South Africa that claims the slowest swim of the year. Conditions at Ironman South Africa have seen the swim canceled or shortened a number of years in the past. It’s certainly not an event where you can expect an easy swim.

Fastest swim times

Slowest swim times

Fastest and slowest Ironman bike times of 2025

The bike is the longest element of the race and has the biggest impact on overall time. In this chart I’ve plotted races’ bike rankings against their overall rankings, and there’s a much stronger relationship between a fast bike and a fast race.

It’s a clean sweep for Europe when it comes to the five fastest bike courses of 2025. Ironman Les Sables takes the top position by 44 seconds. Interestingly, Europe is also home to most of the slowest bike splits of the year: France and Lanzarote are known for their climbs, and Leeds and Wales both possess tough, undulating courses with their fair share of climbs. The notoriously hilly Lake Placid course makes a showing for the U.S.

Fastest bike times

Slowest bike times

Fastest and slowest Ironman run times of 2025

The run is the second longest stage of the race and often where athletes find out if their plans have worked! My final chart plots races’ run rankings against their overall rankings. Like the bike, there’s clearly a relationship between the two, although it’s not quite as well defined.

The men’s Ironman World Championship in Nice tops the list of fastest age-group run times. It clearly shows the impact a selected field has over general entry. Plus, Nice offers a flat run course ideal for fast times with the right weather conditions. The remainder of our fastest runs come from the five fastest races of the year. Of course, it’s mostly European races, but Brazil is also home to a fast run course.

North America dominates the slowest run splits. Ironman Ottawa debuts with a run more than an hour slower than the fastest events. Texas appears to have a particularly slow year for its run. The heat and humidity at Ironman Malaysia always lead to slow run times.

Fastest run times

Slowest run times

These average times and where the races rank in comparison with each other gives a good guide as to where to go for a fast Ironman time (or if you’re looking for a challenging race). Most races are consistent and don’t change their average times or relative rankings much between years.