Burn 500 calories in this workout! You see claims like that everywhere, but how many calories you actually burn depends on a lot more than the exercise itself. Here’s how the numbers really work, and why you should treat them with healthy scepticism.
How calories burned are estimated
The science behind it uses MET values, short for Metabolic Equivalent of Task. A MET rates how intense an activity is compared with sitting still. Sitting is 1 MET; brisk walking is around 4; running is 8 or more.
The formula is simple:
Calories burned ≈ MET × your weight in kg × time in hours
So a heavier person burns more doing the same activity, and longer or harder sessions burn more. Our calories burned calculator handles the maths across a range of activities.
What changes the number
Two people doing “the same” workout can burn quite different amounts, because burn depends on:
- Body weight. More mass means more energy to move it.
- Intensity. Harder effort burns more per minute.
- Duration. Longer sessions add up.
- Fitness and efficiency. Fitter, more efficient movers sometimes burn slightly less for the same task.
- Terrain and conditions. Hills, wind and heat all raise the cost.
Roughly what to expect
Here’s a rough guide for 30 minutes of activity, for a 75 kg person. Scale up if you’re heavier, down if lighter.
| Activity | Approx calories (30 min) |
|---|---|
| Walking (moderate) | ~130 |
| Cycling (moderate) | ~280 |
| Jogging | ~260 |
| Swimming | ~300 |
| HIIT | ~270 |
| Weight training | ~225 |
These are estimates, not promises, real numbers vary with everything listed above.
Why trackers overestimate
Take your watch with a pinch of salt. Fitness trackers and cardio machines are notorious for inflating calorie burn, often by 20 percent or more. They're useful for spotting trends and comparing your own workouts, but poor for precise counts.
This matters most if you’re trying to lose weight. If your watch says you burned 600 calories and you “eat them back”, but the real figure was 400, you’ve quietly wiped out your deficit.
Using it for weight loss
The cleanest approach is to treat exercise as a bonus, not a budget. Rather than eating back what you burn, base your eating on your TDEE and let your deficit do the work. Exercise then adds to the deficit, supports your health and protects muscle, without the guesswork of matching food to burn.
Putting it together
- Estimate burn with the calories burned calculator.
- Treat it as a ballpark, especially anything from a watch or machine.
- Don’t eat it all back if you’re losing weight.
- Let your TDEE and deficit be the main guide.
Exercise is brilliant for your health and a real help for fat loss, just don’t trust any single calorie number too literally.