Macro Calculator

Mifflin-St Jeor Equation

This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), which is then adjusted for activity level and dietary goal. It is considered the most accurate BMR prediction equation for most adults by the Academy of Nutrition and Dietetics.

Male: BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age - 5

Female: BMR = 10 * weight(kg) + 6.25 * height(cm) - 5 * age - 161

Mifflin, M.D., St Jeor, S.T., et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. The American Journal of Clinical Nutrition, 51(2), 241-247.

Macro Distribution

Protein targets are based on the International Society of Sports Nutrition (ISSN) position stand on protein intake (1.4–2.0 g/kg/day for exercising individuals). Carbohydrate and fat amounts are calculated from the remaining calories after protein is set.

Jager, R., Kerksick, C.M., et al. (2017). International Society of Sports Nutrition position stand: protein and exercise. Journal of the ISSN, 14, 20.

Calorie Adjustments by Goal

Cut (-500 cal) and Bulk (+500 cal) are based on the widely used estimate that 3,500 kcal equals approximately 1 lb of body weight, targeting ~1 lb/week change. Lean Bulk (+250 cal) reflects the evidence-based recommendation of a ~10–20% surplus for trained individuals, targeting ~0.25–0.5% bodyweight gain per week to minimize fat gain.

Iraki, J., Fitschen, P., Espinar, S. & Helms, E. (2019). Nutrition recommendations for bodybuilders in the off-season: a narrative review. Sports, 7(7), 154. The 3,500 kcal/lb guideline is a long-standing clinical estimate referenced by the NIH and most major dietetic organizations.