How Many Calories Do I Need? BMR & TDEE Explained

BMR vs TDEE

BMR (Basal Metabolic Rate) is the energy your body burns just to keep you alive at rest — breathing, circulation, keeping warm. TDEE (Total Daily Energy Expenditure) is BMR plus everything else you do: walking, working, exercising, even digesting food. TDEE is the number that actually matters for eating to a goal.

Estimating BMR

The widely used Mifflin-St Jeor formula is: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + s, where s is +5 for men and -161 for women. A 30-year-old man, 80 kg and 180 cm, has a BMR of about 1,780 kcal. The BMR & Calorie Calculator computes it for your figures.

Activity turns BMR into TDEE

Multiply BMR by an activity factor: about 1.2 if sedentary, 1.375 lightly active, 1.55 moderately active, 1.725 very active. A 1,600-kcal BMR becomes roughly 1,900 kcal sedentary, 2,480 moderately active, and 2,760 very active — a wide range that shows why activity level matters as much as the resting figure.

Setting a target for your goal

To maintain weight, eat around your TDEE. To lose weight, eat below it — a deficit of about 500 kcal a day is a common, sustainable pace of roughly half a kilo (a pound) a week. To gain, eat above it by a similar small surplus. Extreme deficits backfire; slow and steady holds.

Frequently asked questions

Are these numbers exact? No — they are solid estimates. Bodies vary, so use the figure as a starting point and adjust based on how your weight actually moves over a few weeks.

Should I eat below my BMR to lose faster? No — eating below BMR for long is hard to sustain and can cost muscle. Base a deficit on TDEE, not BMR.

Does muscle change the number? Yes — more muscle raises BMR, which is one reason strength training helps long-term.