HIIT Calories Calculator
Estimates the calories used in an interval session from your work and recovery intervals, what you do in each, and the number of rounds.
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The formula
average MET = (work MET × work time + recovery MET × recovery time) ÷ (work time + recovery time) gross kcal = MET × weight (kg) × hours net kcal = (MET − 1) × weight (kg) × hours
The session is treated as a time-weighted average of its two parts. Add any warm-up separately.
What to watch out for
Intervals alternate two efforts, so the calculation averages the MET of the work and the recovery by time. The Compendium values used here describe steady effort, so they are a rough fit for short all-out sprints, which lean on energy systems that a steady-state figure does not capture. Choose what you actually sustain, not your best effort. Oxygen use stays raised for a while after a hard session; the effect is real but small, and it is not included.
MET values come from the 2011 Compendium of Physical Activities. Gross calories include what your body would have used at rest over the same time. Net removes that by using MET − 1, so it is the better figure for the extra calories the activity uses. Both are rough estimates, so allow at least ±20%. The true figure varies by person.
Frequently Asked Questions
How many calories does a 20-minute HIIT session burn?
At 70 kg, 20 rounds of 30 seconds at 161–200 W with 30 seconds of slow walking average 6.9 MET. That is about 161 kcal gross, or 138 kcal net of resting.
Does a shorter recovery make much difference?
Yes. Over the same 20 minutes, 40 seconds on and 20 off comes to about 193 kcal gross, against 161 kcal for 30 on and 30 off.
Does HIIT keep burning calories afterwards?
A little. The extra use after a session is modest and fades within hours, so it does not change the picture much.