Triathlon Split Calculator

Your finish time is the sum of five parts: swim, T1, bike, T2, run. Most athletes guess the total and get the bike wrong, which costs them the run. The calculator above takes your pace and speed numbers and returns each split plus the time you cross the line.

What the splits are

Pick your race distance, then feed in the pace you can hold for each discipline. The calculator converts those into a time per leg and adds them up.

• Distance: Sprint (0.75/20/5), Olympic (1.5/40/10), 70.3 (1.9/90/21.1), or Ironman (3.8/180/42.2 km).
• Swim pace per 100m: the pace you can hold for the full swim, not your 50m sprint.
• Bike speed in km/h: your sustainable average for the distance, accounting for the course.
• Run pace per km: the pace you can run off the bike, which is slower than your open-run pace.
• T1 and T2 in minutes: time from water to bike, and bike to run.

Use race-realistic numbers, not your best ever in each. A swim split from a flat pool day will not survive open water and a wetsuit start.

Reading your splits

The total is the headline, but the leg breakdown is where the plan lives. On an Ironman, the bike is roughly five to six hours of your day, so a 1 km/h difference in your assumed speed shifts the total by twenty minutes or more. Run the calculator twice: once with an honest bike speed, once with the speed you wish you could hold. The gap between those two finish times is the cost of going out too hard.

Watch the transitions on the long races. Two minutes in T1 and three in T2 sounds small until you stack them across a full day and a few extra walks through the change tent.

The bike mistake

Going too hard on the bike is the classic way to wreck the run. The legs feel fine at the time. The bill arrives in the back half of the marathon when your pace falls apart and a five-hour bike turns into a six-hour run. Set your bike speed in the calculator below your one-hour time-trial ceiling, hold it on race day, and you keep the legs you need for the run.

Build the engine that holds those splits with the Ironman training plan guide.