Triathlon Calculator

Background.

A triathlon is three workouts stacked back to back, and their energy costs differ enough that a single calories-per-hour figure for the race hides most of the story. Minute for minute, running is the most expensive leg here: at the steady effort this page assumes, a 70 kg athlete spends about 12 kcal per running minute against 9.8 kcal a minute in the water or on the bike. Yet the bike leg usually lasts longest, so it often supplies the biggest share of the total.

Each leg is costed with the metabolic-equivalent (MET) method of the Adult Compendium of Physical Activities — a MET value for the activity, multiplied by body weight and minutes — and the three results are added. Swimming and cycling are both set at 8.0 METs and running at 9.8, fixed moderate intensities rather than anything measured from your session.

That simplicity is also the main limitation. Intensity cannot change, so a hard race effort will usually burn more than the page reports, especially on the bike, where speed, hills and wind change the cost a great deal; an easy training session will burn less. Time in transition is not counted. And because the method is gross, the figure includes the resting energy you would have spent anyway, about 1.2 kcal a minute for a 70 kg adult.

The result is best used for planning: sizing the meals around a long training day, comparing a swim-heavy session with a run-heavy one, or getting a rough sense of what race day costs. A bike power meter will usually pin down that leg more closely for any one athlete.

What is triathlon calculator?

A triathlon calorie estimate is the energy spent across the swim, the bike and the run, each converted from minutes to kilocalories with its own MET value and then summed. A MET expresses an activity's energy cost as a multiple of resting metabolism, defined as 3.5 millilitres of oxygen per kilogram of body weight per minute. The result is gross, with resting energy included, and is in kilocalories, the Calories printed on food labels.

How to use this calculator.

1. 01Enter your body weight in kilograms, ideally your weight on the day; the bike, wetsuit and kit are not part of it.
2. 02Enter the minutes for each leg separately from your watch or the race results. Leave transition time out, since the page does not model it.
3. 03For a training day with only one or two disciplines, set the unused legs to zero.
4. 04Read the total and the split by leg. If you raced well above a steady, moderate effort, expect the real figure to be higher than the estimate.

The formula.

For each leg, kcal = MET × 3.5 × body weight (kg) ÷ 200 × minutes, and the total is the sum of the three legs. The 3.5 is resting oxygen uptake in millilitres per kilogram per minute, which defines one MET; dividing by 200 converts millilitres of oxygen into kilocalories, because a litre of oxygen releases close to 5 kcal. The MET values are fixed at 8.0 for swimming, 8.0 for cycling and 9.8 for running, so swimming and cycling cost the same per minute and running costs 22.5% more. Everything scales in proportion: double the body weight or the minutes and the calories double. That is why the leg you spend longest on, usually the bike, tends to dominate the total. A leg set to zero minutes simply drops out.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Adult Compendium of Physical Activities. 2024 Adult Compendium. Activity-specific metabolic equivalent codes. Retrieved 2026-08-06.
2. [2]U.S. National Library of Medicine. PubMed record current 2026-08-06. Indexed derivation and validation literature. Retrieved 2026-08-06.
3. [3]World Health Organization. Patient safety resources current 2026. Clinical decision-support safety context. Retrieved 2026-08-06.