IM Mara vs. Standalone

    • 5-10%
    • 10-15%
    • 15-20%
    • 20-25%
    • 25%

0 voters

Day dreaming a bit really after my run earlier. I know there are loads of variables - course, how you biked, weather, nutrition, relative SBR strength etc etc - but as a general figure, what are your typical differences between IM and standalone mara times.

If you’ve not properly raced a mara standalone, then roughly what do you think it would’ve been on a similar profile of course?

Yuge numbers you’re asking me to juggle here

One hour is fifth of five hours so 30mins is one tenth or 10%

Elite level then :trophy:



Have i made my spans too wide?

Actually, no. That’s just good conversion.

You could have a 3hr runner respectfully doing 4 at IM. That would be a 33% increase and perfectly reasonable i’d guess? Not sure.


I’ve never done a stand-alone - but my IM Mara times are embarrassingly way over 25% what I’d expect.

  • Weather (notably hotter than the sun outlaw). I don’t like running in the heat at best of times. Not many standalone maras starting around lunchtime!
  • Injury (prob wouldnt have towed the start line for a stand alone with the limited long runs I’d done)
  • Nutrition (hydration breaking on bike - very ill before and during run).

Ironically the one I was least prepared for (injury) gave me my best time - prob as I had a plan going in and for 18-20 miles it largely worked. Till the wheels expectedly fell off.


Years ago there was a table that someone had compiled with a fairly decent assessment of this. I think it may have been on Slowtwitch.

See if I can find it

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That would be you over-biked!


I guess so, yeah. But there are loads of sub 3 athletes (or am i making a wholesale assumption here). Plenty of which will enter an IM. Yet you don’t see a huge number of mara times under 3.30 really.

These are just high level musings at the mo. I’ve not looked into it properly at all.


Oohh i did a Chat GPT

There is no fixed average drop-off between a standalone marathon and an Ironman marathon, as it can vary depending on individual factors such as fitness, training, and experience. However, research suggests that the physical and mental demands of swimming and cycling in addition to running can result in a slower marathon time during an Ironman race.

One study conducted by Lepers and colleagues (2011) found that the average marathon time of Ironman athletes was approximately 10-20% slower than their personal best standalone marathon time. The study looked at 36 male Ironman triathletes who had completed both an Ironman race and a standalone marathon within the previous 12 months.

Another study by Wüthrich and colleagues (2019) found that the average marathon time for participants in Ironman Switzerland was around 24 minutes slower than their personal best standalone marathon time. The study looked at 157 male participants in Ironman Switzerland who had completed at least one standalone marathon in the previous three years.

It’s worth noting that these studies have limitations and may not be representative of all triathletes or Ironman races. Additionally, there are many factors that can influence marathon performance in an Ironman race, such as the course terrain, weather conditions, and nutrition strategy.


Lepers, R., Knechtle, B., Stapley, P., & Andonie, J. (2011). Analysis of Hawaii ironman performances in elite triathletes from 1981 to 2007. Medicine & Science in Sports & Exercise, 43(2), 337-343.

Wüthrich, T. U., Marty, J., Kerherve, H. A., Millet, G. P., & Verges, S. (2019). Influence of an Ironman triathlon on running mechanics, muscle oxygenation, and energy cost: a field study. Sports Medicine-Open, 5(1), 1-9.


30 minutes


loves me a science fact

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26 ( mins) for the age group elite!

But half hour is quite a common response.



ponders the implications

Cant find the ST thread and dont like spending too much time in there, makes me feel dirty.

Since i have never ran a marathon nor done an Ironman I have little to add :slight_smile:


No, just no.

Best ever stand alone 3:04. I have 7/8 marathons between 3:10 and 3:15.

Best IM Mara 3:29. I have a bunch of decent IM maras around 3:40-3:45.

The ones around 4 hours were fuck ups for various reasons .

So 30 mins for me as long as I execute the IM well.


Pretty similar to Chris for me, unless I have a meltdown or too many bog stops it tends to be 30-40 minutes.


About 30 mins also


I think the problem with the study is it takes IM athletes who have done a marathon in the same 12 months, so likely it is not going to be their ‘best’ possible stand alone marathon.

I also don’t think you can put a % on the decline, because slower runners are not going to slow down as much as faster runners (relatively speaking)

Hence, 30 minutes, or ~1min/ml in old money.

Assumes there is no complete implosion and walking it in from 10K!


Best standalone 2:52, only IM marathon 4:50 :laughing:


Yeah, I was just messing about with that post using the AI. That’s why I was hoping for more real world thoughts and feelings around it.

I’ve got months to go so I’m just day dreaming! :joy: I’ll probs be under trained or injured anyway , so it probably won’t matter!