A Detailed Update on the Boston Marathon Cutoff From December to January

Since the fall, I’ve been collecting data to project the cutoff time for the 2026 Boston Marathon. I’ve put together a Tableau dashboard to help you explore the data in real time, which you can play with here.

While that tracker is updated on a weekly basis, I take a step back from time to time to do a deep dive on what has changed. I published my last detailed analysis in December, and that was focused on data through the weekend before Thanksgiving.

This week, I published a follow up that explores the data from late November through late January. Among other things, this includes the Houston Marathon and CIM. These are the last two really big, fast marathons until later in the spring.

The full analysis is published in Runner’s Life on Medium. If you’re not a Medium subscriber, you can request a special link to read the article here.

In the meantime, I’ll share a quick summary of the key findings below.

What Are the Trends In the Data?

From late November to late January, I added 26 additional races to my dataset.

This included some very large races (Honolulu, Disney, CIM, Houston), some moderately large races (Dallas, Rock ‘n’ Roll San Antonio, Seattle, Memphis), and some smaller races with only a few hundred finishers.

Across the board, almost all of these races saw an increase in the number of finishers. Many races saw an increase of more than 20%. Houston saw a more muted increase of around 5.5%.

The three races that saw a decline in finishers were CIM, Memphis, and Disney. In the context of the Boston cutoff, CIM is the most important. The number of finishers dropped 8.8% from last year – although this year’s field of finishers was still the second largest in the history of the race.

Across the board, the total number of qualifiers was down about 20% compared to last year. This is driven by a) the tougher qualifying times and b) the large drop in finishers at CIM.

Aside from CIM, Houston saw the second highest drop in the number of qualifiers. Although it’s field grew, it didn’t grow enough to offset the tougher qualifying times – and the number of qualifiers dropped by 16% compared to last year.

Predicting the Cutoff from the Change in Qualifiers

In the analysis, I get more in depth with the math. But here’s the core assumption.

If the number of qualifiers stays the same, the number of applicants will stay the same. Therefore, the cutoff time will be roughly the same.

To round things off and make for easy estimations, a 5% decrease in the number of finishers is roughly equivalent to one minute of cutoff.

So …

• No decrease = 7:00
• -5% = 6:00
• -10% = 5:00
• -15% = 4:00
• -20% = 3:00
• -25% = 2:00
• -30% = 1:00
• -35% = No cutoff

The decrease during this time period alone is roughly 20% – which if that were extended to the entire qualifying period would lead to a ~3:00 cutoff.

But given the fall races that have already taken place, when this gets factored into the big picture, the number of qualifiers is still only 7% lower than last year. This is solidly between the 5:00 and 6:00 levels.

This also illustrates a final point worth keeping in mind. With about half of the races for this qualifying period complete, the ultimate result is already anchored around 7%. It will take an extremely large difference to pull it far in one direction or the other.

If the remainder of the qualifying period saw a 20% decrease in qualifiers, that would only move the needle down to ~15%. To get down to a 3:00 cutoff would require that the number of qualifiers through the remainder of the qualifying period dropped drastically – by 30% to 40%.

Other Wildcards to Consider

I ended the analysis with four wildcards that you may want to consider. They are four individual races that could impact the ultimate outcome.

First, Berlin. It accounted for a significant portion of the increased number of finishers and qualifiers. This could cause the estimate of qualifiers to be inflated. It would be silly to exclude this race altogether, but if you did … the resulting projection would still be over 4:00.

Second, Chicago. It lost a large number of qualifiers this year. In large part, this is due to the age group championships – which was at Chicago in 2023 and at Sydney in 2024. This could cause the number of qualifiers to be artificially lowered, since the age group championships aren’t currently in the sample. Excluding Chicago would push the cut-off time projection to almost 6:30.

Third, Sydney. It’s on the other side of the world, and it’s not currently in the sample. But the 2024 was race much larger than 2023, and it included the age group championships. It also included more international runners, including many from the US and the UK. And the 2025 Sydney Marathon is at the end of August, putting both 2024 and 2025 in this qualifying period. This is potentially a large pool of additional qualifiers that’s currently not accounted for in the projection.

Fourth, Boston. It’s always a big question mark, as it’s the number one source of Boston qualifiers. But keep in mind that 2024 was a down year for Boston due to the weather. You should expect the results at this year’s race to be much faster.

What’s Left to Come?

We’re about halfway through the current qualifying period – both in terms of races and in terms of finishers.

There are some moderately impactful races in February and March. But for April is the big month – between Boston, London, and several other fast races. By the end of April, things will start to become more clear and less hazy.

From here on out, the best case scenario is probably that the number of qualifiers at the remaining races drops 15-20%. This assumes that growth among the spring races starts to plateau. This rosy pictures would put the cutoff time somewhere around 4:00.

Worst case scenario – if there’s great weather at Boston and races continue to grow rapidly – it could sneak up to the 6:00 range. But I think this is unlikely.