Ironman Race Time Predictor
Predict your Ironman finish time from swim, bike, and run paces.
Covers full Ironman, 70.3 half, Olympic, and sprint triathlon distances.
A triathlon finish time is simply the sum of three leg times plus two transitions:
Total = Swim time + T1 + Bike time + T2 + Run time
Race distances:
- Sprint: 750m swim | 20km bike | 5km run
- Olympic: 1.5km swim | 40km bike | 10km run
- 70.3 Half Ironman: 1.93km swim | 90.1km bike | 21.1km run
- Full Ironman: 3.86km swim | 180.2km bike | 42.2km run
Swim pace is entered in minutes per 100m, which is the standard unit for pool and open-water swimming. A 2:00/100m pace is moderate for a triathlete; 1:30/100m is competitive for the swim leg.
Bike speed in km/h (20–25 for beginners, 30–35 for experienced athletes). The bike leg is where most time is won or lost in a full Ironman.
Run pace in minutes per km. Open-water swim fatigue and several hours on the bike make the run pace considerably slower than your standalone run — typically 10–20% slower for experienced athletes, more for beginners.
Typical transition times:
- T1 (swim to bike): 3–8 minutes (stripping wetsuit, getting helmet, mounting bike)
- T2 (bike to run): 2–4 minutes (racking bike, changing shoes)
Kona finishers average about 1:10/100m swim, 40 km/h bike, and 4:00/km run pace. Age-group qualifying times vary by division — the cut-off for many 35-39 age groups is around 9:30–10:00 total.
How we build and check this calculator
This calculator runs entirely in your browser, so the numbers you enter stay on your device. The math behind it is written by hand and tested against worked examples and standard references before the page goes live.
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