Basal metabolic rate (Mifflin-St Jeor), daily energy need with five activity levels, calorie targets for losing, holding and gaining weight, plus macros in grams — metric or US units.
| Goal | kcal/day | Protein | Fat | Carbs |
|---|
Basal metabolic rate uses the Mifflin-St Jeor equation, the formula most dietitians use for adults: 10 × weight(kg) + 6.25 × height(cm) - 5 × age + 5 for men and - 161 for women. The activity factor (1.2 to 1.9) turns that into the total daily energy expenditure. A deficit or surplus of 500 kcal per day corresponds to roughly 0.45 kg of body fat per week, assuming 1 kg of fat equals about 7,700 kcal. These are estimates: real needs vary with body composition, medication and health. This is general information, not medical advice — many guidelines put the floor at about 1,200 kcal for women and 1,500 kcal for men, so a warning appears below that.
The calculator works in three steps. First the basal metabolic rate: the energy your body uses at complete rest, from the Mifflin-St Jeor equation from weight, height, age and sex. For a 30-year-old man of 80 kg and 180 cm that is 1,780 kcal; the same woman would get 1,320 kcal. Second the total daily energy expenditure, which multiplies the basal rate by an activity factor: 1.2 for a desk job, 1.375 for light exercise one to three days a week, 1.55 for three to five days, 1.725 for six to seven days and 1.9 for hard daily training or physical work. Third the calorie target: 500 kcal below the daily need to lose, the need itself to hold, 500 kcal above to gain. Each target comes with protein, fat and carbohydrate in grams, using a 30/30/40 split for losing, 25/30/45 for holding and 25/25/50 for gaining. Values can be entered in kg and cm or in pounds and feet with inches.