Calorie Calculator

How Your Calorie Needs Are Calculated

The calculator works in two steps. First it estimates your Basal Metabolic Rate with the Mifflin-St Jeor equation — for men BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5, and for women the same equation ending in − 161. Then it multiplies BMR by an activity factor to produce your Total Daily Energy Expenditure (TDEE), the calories you burn on a typical day.

Understanding BMR, TDEE, and Activity Factors

Your BMR alone often accounts for 60-70% of the calories you burn. The remainder comes from movement, formal exercise, and the energy used to digest food. The activity multipliers range from 1.2 for sedentary to 1.9 for extremely active. Because these factors span a wide range, an honest assessment of your week matters: overstating activity is the most common reason a plan stalls.

Using Calories for Weight Goals

Weight change is driven by energy balance. Eating below your TDEE creates a deficit and your body draws on stored fat; eating above it creates a surplus for growth. Because roughly 3,500 calories equal about one pound of body fat, a steady 500-calorie daily deficit projects to about 1 lb per week. Gradual changes of 0.5-1% of body weight per week are more sustainable and better preserve muscle than crash dieting.

Accuracy and a Note on Health

These equations are population estimates: real metabolism varies with genetics, muscle mass, hormones, medications, and non-exercise activity, so treat the number as a starting point and adjust based on how your weight actually trends over 2-4 weeks. This tool is for general education, not medical advice — if you are pregnant, managing a health condition, or planning a significant diet change, consult a doctor or registered dietitian first.