HIIT Calories Burned Calculator (with Afterburn)
Calories burned in a high-intensity interval session from work/rest intervals, intensity and body weight — including the EPOC afterburn — compared with steady cardio of the same duration.
How it works
kcal/min = MET × 3.5 × kg ÷ 200; work at 8–15 MET, rest at 3.5 MET, warm-up 4 MET; EPOC ≈ 7–14% of session calories depending on intensity
Interval training alternates bursts near maximal effort with recovery, and its calorie cost is the sum of both: the bursts burn at 10–15 METs — as much as fast running — but only for a fraction of the session, while recovery periods tick along at little more than standing. Averaged out, a 20-minute Tabata-style session lands near a hard steady run of the same length, not far above it. HIIT’s extra comes from excess post-exercise oxygen consumption, the elevated metabolism while the body clears lactate, replenishes phosphocreatine and repairs tissue; research puts it at roughly 6–15% of the session’s calories, higher after true sprints. The real advantages of intervals are time efficiency and fitness gains per minute, not dramatically more calories.
Worked example
75 kg, 20 rounds of 40 s hard / 20 s rest at 12 MET with 8 minutes of warm-up and cool-down: about 283 kcal in 28 minutes, plus ≈ 40 kcal of afterburn — versus about 257 kcal for a steady jog over the same 28 minutes.
Frequently asked questions
Is the afterburn really significant?
It is real but modest — tens of calories, not hundreds. Claims of 500+ kcal afterburns are not supported by measurements.
How often can I do HIIT?
Two or three sessions a week is what most guidelines and studies use; more than that raises injury and overtraining risk without extra benefit for most people.
Related calculators
General fitness estimate, not medical advice. Calorie and performance figures vary widely between individuals — use them for planning and comparison, and check with a doctor before starting intense training.