The short answer
A 70 kg person doing moderate HIIT burns roughly 310 calories in 30 minutes (MET 8.8). Lighter people burn less, harder intervals burn more, and a strong afterburn (EPOC) means your total daily burn is higher than the session alone. The chart and calculator below break it down by your exact weight, intensity, and time.
HIIT is prized for packing a big burn into a short window, which is why it dominates time-crunched training plans. But "calories burned during HIIT" is not a single number. It scales with three things: how much you weigh, how hard your intervals are, and how long you keep going, plus an afterburn that most calculators skip entirely.
The science behind the numbers is the MET (metabolic equivalent). Each intensity has a MET value from the 2024 Adult Compendium of Physical Activities, and the formula is simple: calories = MET x your weight in kilograms x hours. We did that math for every common weight and intensity below.
How many calories does HIIT burn?
Pick the row for your session time and the column for your weight. Easy is moderate intervals around MET 7, moderate is indoor cycling style HIIT around MET 8.8, and fast is vigorous intervals around MET 11. The harder you push during the work bouts, the higher the MET, and the more you burn for the same time.
Why your weight matters
HIIT involves moving and accelerating your own body, so the heavier you are, the more energy each interval costs. That is why every row in the table rises as you move right across the weight columns. A 100 kg person burns roughly twice the calories of a 55 kg person at the same intensity and time, with no extra effort, simply because there is more mass to move. This is also why two people in the same class finish with very different numbers.
Why intensity changes the number
HIIT lives or dies on intensity. The whole point is that the work intervals are near maximal, which pushes oxygen demand and the MET value up sharply. Going from moderate intervals (MET 7) to vigorous ones (MET 11) raises the burn by more than half for the same time. The catch is honesty: a session where the rest periods stretch out and the work bouts go soft is not really HIIT, and the MET drops toward ordinary cardio. The number on the chart assumes you actually hit the high end during the hard intervals.
What about the afterburn (EPOC)?
This is where HIIT earns its reputation, and it is worth being honest about the size of the effect. EPOC (excess post-exercise oxygen consumption) is the extra energy your body spends after a hard session restoring oxygen, clearing metabolites, and repairing muscle. Because HIIT pushes you into oxygen debt repeatedly, it generates more EPOC than steady cardio, so your metabolism stays slightly elevated for hours afterward.
The honest caveat: the afterburn is real but modest. Research puts it at roughly 6 to 15 percent on top of the session burn, not the wild multipliers some marketing claims. So a 310 calorie HIIT session might total closer to 330 to 360 calories once the afterburn is counted. It is a genuine edge over steady cardio, just a smaller one than the hype suggests. The chart and calculator below show the session burn; treat the afterburn as a real bonus on top.
Calories burned vs calories eaten
Knowing you burned 310 calories in a HIIT session, plus a little afterburn, is only half the picture. What you do with that number is what changes your weight or your performance. HIIT also tends to spike appetite, so it is easy to eat back the entire session and then some without noticing. The useful move is to connect the burn to your intake for the day, which is exactly the gap a coach fills.
Log your HIIT sessions without the math
Reading a chart is one thing. Tracking every session, day after day, especially when you are wiped out afterward, is where most people give up. With CalAlly you say "I did 25 minutes of HIIT" and it logs the activity, estimates the burn, and folds it into your daily numbers. The built in AI nutrition coach then tells you what to eat to match your training and ride out the post-session hunger, so the calories you burn actually serve your goal. See what CalAlly is, the best calorie tracker for HIIT, or our best calorie tracker apps roundup.
