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What is the Ironman World Record? It’s Complicated

Hint: There isn't really an Ironman world record. But there are some fastest-known Ironman times.

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This weekend, Olympic champ Kristian Blummenfelt made his Ironman debut at Cozumel in a world record performance of 7:21:12—with a 39:41 swim, 4:02:40 bike, and a 2:35:24 run. Wait, you’re thinking (among other things): “He swam how fast? Is that right?!” The performance prompted much speculation online about the current-aided swim; what constitutes an Ironman world record, Ironman best, or Ironman course record; and how exactly these records are measured. How does this stack up to previous Ironman world bests? And is it the new official Ironman world record?

Let’s start with the first thing first: There is no such official thing as an Ironman world record—not that that stops people from keeping unofficial records. And, yes, Blummenfelt’s 7:21 is the unofficial fastest-known Ironman or iron-distance time—ie. for most intents and purposes, it’s a new Ironman world record (on his first attempt at the distance).

The women’s champion at Ironman Cozumel, Sara Svensk, also set a new unofficial fastest-known Ironman-brand time—ie. an Ironman-brand “world record”—of 8:22:41. So, what does this all mean for the record books?

How Ironman world records work

In running, official world records have to meet certain criteria, including course certification, requirements around how many athletes must be in the event, drug testing, and even whether women were racing alone or if it’s a co-ed event. These record-setting standards do not exist in triathlon. And while course distances are confirmed in high-level World Triathlon racing (i.e., the Olympics—though even at the Rio Games, the bike course was stated to be short), there is no course certification for long-course or for regular age-group races of any distance. It’s approximately 70.3 or 140.6 miles, but who’s really checking?

Ironman officials confirmed that they do not keep official world or course records for these reasons—because of variations in courses from year-to-year and from course-to-course, and because of the lack of official course certifications.

“Due to variance of courses (even from year-to-year the same race could have course alterations), combined with the fact that unlike marathons, triathlon does not have official course certification for records, we use world best, course best, race best, swim/bike/run course best, etc.,” said an Ironman spokesperson.

For what it’s worth, the Guinness World Records recognizes the “fastest time to complete an Ironman triathlon” (funnily, a record that was previously, before Blummenfelt’s performance, set at Challenge Roth), the Ironman World Championship fastest time, and a whole host of other triathlon-related things, like the fastest time to complete an Ironman blindfolded or the most siblings to complete an Ironman or the largest triathlon race (Nation’s Triathlon in 2010).

ironman world record fastest time
Chrissie Wellington wins with the fastest female iron-distance time ever at Challenge Roth in 2011. Photo: Getty Images

OK, but what are the fastest Ironman times?

Sure, sure, you’re thinking, there’s not an official Ironman world record, but there are still times that everyone knows are the fastest—and isn’t that basically just as good?

This is where it tends to get even a bit more complicated. Earlier this summer, Jan Frodeno set a “world record” Ironman time of 7:27:53. It was truly a stunning physical performance and was the world leading time at the time, but was it a world record? Frodo did it in a two-man exhibition event that was designed for fast times and had quirks like a velodrome-style turnaround and motorcycles that handed him water bottles while he biked. Does that meet the standard of an actual race? He did have to actually do the whole thing by himself, but he didn’t have to deal with the indignities of a regular race, competitors, aid stations, transition areas, and all that goes with that.

Similarly, the Sub7/Sub8 project is modeling itself off the Breaking2 marathon spectacle and attempting to answer the question of if a man can go sub-7 and a woman sub-8—but they’ll allow drafting and specialized courses picked for ideal conditions. Does that then meet the standards of a record?

RELATED: Can A Triathlete Really Break 7 Hours Over the Iron-Distance?

In a much simpler vein, there are also courses that are simply known to be fast—Ironman Brazil, Challenge Roth, Bahrain 70.3—and those that are known to not be fast—Kona, for instance (making Daniela Ryf’s performance there in 2018 even more impressive—even with it being a “fast” year). For instance, Ironman Cozumel this year had notably fast swim times with a heavy current, leading to Blummenfelt’s 39-minute 2.4-mile. For what it’s worth, second place Ruedi Wild came out of the water with Blummenfelt, and finished in a time (7:36:35) that would have also broken the existing “unofficial” Ironman world record. And the women’s winner, Svensk, also set a new Ironman-brand world record. The course, it appears, was fast–whatever the reason.

Then, there are the issues around when a course gets shortened or modified. In 2018, Ironman said they would recognize the times set at Ironman Texas as “world’s best” and “course best” times despite the bike course being shortened—leading to much debate. They had initially said course record times set would come with an asterisk. Both the previous world’s fastest Ironman-brand times were set there by Matt Hanson (7:39:25) and Melissa Hauschildt (8:31:05).

And we haven’t even talked about the impact of drafting in regular race settings. All of that being said, these are the fastest known world leading times. Check out even more detail on historical records broken down at

Fastest Ironman time:

  • Men: 7:21:12 – Kristian Blummenfelt (IM Cozumel, 2021)
  • Women: 8:22:41 – Sara Svensk (IM Cozumel, 2021)

If you don’t count Texas that year, since it was controversially short, and look past Cozumel this year, until it becomes official-ish, then you have to also look at the next best:

  • Men: 7:40:23 – Tim Don (IM Brazil, 2017)
  • Women: 8:26:18 – Daniela Ryf (IM World Championships in Kona, 2018)

Fastest non-Ironman brand time:

  • Men: 7:35:39 – Jan Frodeno (Challenge Roth, 2016)
  • Women: 8:18:13 – Chrissie Wellington (Challenge Roth, 2011)

Fastest Ironman World Championship course record:

  • Men: 7:51:13 – Jan Frodeno (2019)
  • Women: 8:26:18 – Daniela Ryf (2018)

Fastest half-Iron distance:

  • Men: 3:25:21 – Kristian Blummenfelt (Bahrain 70.3, 2019)
  • Women: 3:52:51 – Holly Lawrence (Bahrain 70.3, 2019)

A few weeks ago, Blummenfelt’s countryman Gustav Iden also put in an impressive debut performance of 7:42:57 at Ironman Florida that left many talking about a possible Ironman world record. (It was the fastest known Ironman debut on record at the time, until his training partner came along to top him, and would have put him in the top five Ironman performances.) But with an exceptionally slow swim in Florida, that 7:42 starts to look not so dissimilar from a 7:21 with an exceptionally fast swim–making a strong case for why course-to-course comparisons are key in triathlon record discussions. And making everyone eager for the Kristian-Gustav-Jan head-to-head match-ups to come.

This article was originally published on Nov. 10, 2021 and has been updated.