Pick the race, not just the training plan.

Why I built this

You get a few races a year, at most — and they’re expensive. Entry fees, travel, and months of training go into every one. Of course it’s about the journey: getting better, staying active, having fun, competing. But part of it is trying to achieve something.

Before The Threshold Report, choosing where to race meant Reddit threads and word of mouth. You don’t know who’s on the other side of the thread, whether they’re any good, or whether their experience translates to you.

I built this to answer my own question: where should I race to give myself the best chance of making the IRONMAN World Championship? I’m shy and I’m a nerd, so I started with the data.

You shouldn’t have to do the data wrangling and modeling yourself. You have enough to worry about.

What you can do

• Search every qualifying race by distance, region, date and distance from home — with each race’s slots, field size and cutoff.
• See your chances at each race. Claim your past IRONMAN results and every race is scored against your age-graded best, adjusted to that course.
• Compare up to four races side by side — qualifying, your chances, your age group, the course and race-day conditions.
• Follow races you’re considering and keep them on your profile with their dates and registration status.
• Know your strengths — swim, bike and run percentiles against all age-groupers, and the courses that suit them.

Compare races side by side

Picking between two or three races is where most of the value is. Add races with + Compare on race search or any race page, then open the comparison from the bar at the bottom of the screen. The best value in each row is highlighted.

On paper IRONMAN Lanzarote’s cutoff is 13 minutes slower — it looks like the easier slot. But the course plays 11% slower than average. Put both cutoffs on an average course and IRONMAN Lanzarote is the harder one to qualify at. That’s the kind of thing a side-by-side comparison makes obvious. Signed in, it also shows your projected time on each course, your chances, and your age group’s results.

How the numbers work

The qualification cutoff

Every qualifying race has a fixed number of World Championship slots for men and for women. Each age group’s winner gets one; we assume about 70% of winners accept (the usual IRONMAN figure). The rest of the slots go to the fastest remaining finishers across the whole gender field, ranked by age-graded time. We replay that with the race’s actual results, finisher by finisher, and the last qualifier’s age-graded time is the cutoff — what you’d have needed to beat if you didn’t win your age group.

Age-graded time

IRONMAN ranks the performance pool by age-graded time: your finish time multiplied by your age group’s standard factor, so a 55-year-old and a 32-year-old can be compared fairly. We use IRONMAN’s 2026 factors for every year, so results from different seasons line up.

How fast a course plays

Raw finish times mix up the course, the field and the weather. To separate them we follow athletes who raced more than one course: if the same people are consistently 14% slower at one race than everywhere else, that course plays 14% slow. This gives each course — and each leg — a speed factor with field strength and that day’s conditions taken out. It’s refreshed weekly as new results come in.

On race pages this shows up as how fast it plays (overall), leg by leg (a typical split here and how many minutes it is over or under a typical course) and where strong athletes gain time.

Your chances

Your best age-graded result is converted to an average course, then projected onto each race’s course and compared with its cutoff:

• Perfect Match — your projected time beats the cutoff
• Strong Chance — within 5%
• Realistic Reach — 5–15% slower
• Stretch Goal — 15–30% slower
• Long Shot — more than 30% slower

Only raced one distance? We estimate the other from athletes who’ve done both (adjusted for age group), and show a range that 8 in 10 athletes fall inside. An estimate is never called a Perfect Match unless the whole range is under the cutoff.

Race badges

• Easy Field — among the most slots per finisher at that distance (top quarter of races), judged separately for men and women.
• Fast Course — the course plays at least 2% faster than an average course.
• Best Bet Overall — both.
• Competitive — among the fewest slots per finisher (bottom quarter).

Race-day conditions

For each race we look up the weather at the venue on its past race days: temperature and “feels like”, humidity (as dew point, which decides how much heavy sweaters suffer), wind during the bike, rain and — for sea swims — water temperature with the likely wetsuit call under IRONMAN age-group rules.

Where the data comes from

• Results: about 1.9 million IRONMAN and IRONMAN 70.3 finisher results, updated as new races are published.
• Slots, dates and registration: IRONMAN’s published qualifying-race lists and race pages, checked daily.
• Weather: Open-Meteo.com (CC BY 4.0) historical weather and sea temperature.

The Threshold Report is independent and not affiliated with or endorsed by IRONMAN.

What to keep in mind

• Cutoffs come from a race’s most recent results. Slots, fields and roll-downs change year to year, so treat a cutoff as a strong guide, not a guarantee.
• New races, and races without recent results, don’t have a cutoff yet — they’re listed with their slots and marked “no qualification data yet”.
• World Championship results (Kona, Nice, 70.3 Worlds) count towards your profile but aren’t adjusted for their course yet.
• Weather comes from a grid about 10–25 km wide, so coastal and island venues can read a little cool. Water temperature is only available for sea swims.

Tell us what to build next

The Threshold Report is in beta and built around what athletes ask for. Signed-in members can suggest and vote on features on the roadmap.