Ironman Pace Calculator

How it is calculated

The tool adds three legs over the full Ironman distances it uses: a 3.86 km swim, a 180.25 km bike and a 42.2 km run.

swim time (s) = swim pace × 38.6, with swim pace in seconds per 100 m

bike time (s) = 180.25 / bike speed × 3600, with speed in km/h

run time (s) = run pace × 42.2, with run pace in seconds per km

The total is the sum of the three, shown both in hours with two decimals and in whole seconds. Transitions (T1 and T2), waiting and toilet stops are not included, so add them yourself, as the tool gives moving time only. All three values must be above zero. Real race pace is not constant, and most people slow down in the run, so use a pace you can hold for the entire leg.

Common mistakes

• Entering the swim pace per 100 yards, or as minutes and seconds (1:50), instead of seconds per 100 m (110).
• Typing a run pace in min/km (6) instead of seconds per km (360). The tool accepts it, so the finish time comes out several hours too short.
• Using a short-ride speed for the bike. A fast 40 km/h from a 1-hour effort cannot be held for 180 km, and the bike speed is the biggest lever on the total.
• Entering the pace of a fresh standalone marathon for the run leg. After a 180 km ride the run is usually slower.
• Reading 11.03 h as 11 hours and 3 minutes. The decimals are a fraction of an hour (0.03 h is about 2 minutes), and transitions will add 10 minutes or more.