Fitness trackers use heart rate, motion sensors, and proprietary algorithms. MET-based calculations use standardized values for the activity type. Neither is perfectly accurate — expect 15–30% variation between methods.

No. This calculator estimates calories burned during the activity only. Post-exercise oxygen consumption adds a modest amount (5–15% for HIIT, less for steady-state cardio) but is difficult to quantify precisely.

If you've lost weight, your lighter body requires less energy to move. Additionally, improved fitness means your body works more efficiently, reducing calorie burn for the same activity. This is normal adaptation.

Per minute, strength training burns fewer calories than cardio. But it builds muscle, which increases resting metabolic rate. The long-term metabolic benefits of muscle often outweigh the acute calorie burn of cardio.

Use it as one input among many. Calorie burn estimates have wide error margins (±20%). Track weight trends over 2–3 weeks and adjust intake based on actual results, not just calculator estimates.

Moving a heavier body requires more energy. Walking a mile at 100 kg burns significantly more than at 60 kg. This is why calorie burn for the same activity decreases as you lose weight.