BMR vs TDEE: the two numbers people mix up when setting calorie targets

One is what you'd burn lying still all day - the other is what you actually burn

Basal metabolic rate (BMR) is the energy your body would burn over 24 hours doing absolutely nothing but staying alive - breathing, circulating blood, maintaining organ function, at complete rest. It's a theoretical floor, not a real-world number, and it typically accounts for 60-75% of total daily energy expenditure for a sedentary person, more for someone very inactive, less for someone very active.

Total daily energy expenditure (TDEE) is BMR plus everything else: digesting food (the thermic effect of food), structured exercise, and non-exercise activity like walking, fidgeting, and daily movement (NEAT). TDEE is the number that actually matters for setting a calorie target, since it reflects what you really burn in a day, not the artificial floor of BMR. Using BMR as if it were your maintenance calorie level is a common mistake that leads to under-eating and drastically underestimating actual needs.

The practical use: calculate BMR as a starting reference point, then multiply by an activity factor to estimate TDEE, and adjust from there based on real-world weight trends over a few weeks - any formula is an estimate, and your own tracked results over time are more accurate than any calculator.