Macro Calculator: Calories and Macros per Day

How the macro calculator works

First, basal metabolic rate is estimated with the Mifflin-St Jeor equation (Mifflin et al., 1990) and multiplied by the PAL value to get total daily energy expenditure. The calculator then adjusts calories to your goal and splits them into macronutrients in this order: protein first, then fat, and carbohydrates fill the rest.

Calories by goal

Lose fat: Helms et al. (2014) cite a loss of 0.5 to 1 percent of body weight per week during a diet. The calculator uses the lower bound of 0.5 percent and roughly 7,700 kcal per kilogram of body fat. Build muscle: Iraki et al. (2019) recommend a calorie surplus of about 10 to 20 percent above maintenance; the calculator uses the lower value of 10 percent. Maintain: calories equal estimated total expenditure.

Protein, fat and carbs

Protein: for maintaining and building, the calculator uses 1.6 g per kg of body weight – the point beyond which Morton et al. (2018) found no further gains in fat-free mass. In a calorie deficit it uses 2.3 g/kg, the lower end of the ISSN range for resistance training during hypocaloric periods (Jäger et al., 2017). Fat: the joint position statement by the ACSM and dietetic associations cites 20 to 35 percent of energy intake; the calculator uses 25 percent. Carbohydrates fill the remaining calories.