All formulas used by Calvor

METHODOLOGY

The Formulas

Four equations. Each with a different history, different assumptions, and different ideal use cases.

011990

Mifflin-St Jeor

The modern gold standard

Accuracy

Developed by MD Mifflin and ST St Jeor, this equation was derived from a study of 498 healthy adults. It consistently outperforms older equations in predicting resting metabolic rate and is the formula most recommended by dietitians today.

EQUATION
♂ Male(10 × kg) + (6.25 × cm) − (5 × age) + 5
♀ Female(10 × kg) + (6.25 × cm) − (5 × age) − 161
kgBody weight in kilograms
cmHeight in centimetres
ageAge in years
STRENGTHS
  • +Validated across large, diverse populations
  • +No body fat % measurement required
  • +Most accurate for average body compositions
LIMITATIONS
  • Less accurate at extremes of body fat
  • Does not account for lean mass directly
BEST FORMost people — general population
03

REFERENCE_GUIDE

< 18.5UNDERWEIGHT

Possible nutrient deficiency or underlying health issues.

18.5 – 25HEALTHY

Ideal balance of weight relative to height. Lower risk of disease.

25.0 – 30OVERWEIGHT

Increased risk for cardiovascular stress and metabolic issues.

≥ 30.0OBESE

Significant risk for type 2 diabetes, hypertension, and heart disease.

THE FORMULA

BMI is calculated as kg/m2. It provides a simple numeric measure of a person's thickness or thinness, allowing health professionals to discuss weight problems more objectively with their patients.

LIMITATIONS

While useful for populations, it does not account for age, sex, bone structure, or fat distribution (visceral vs. subcutaneous), which are all critical markers of metabolic health.

IMPORTANT_ADVISORY: MUSCLE_DENSITY

BMI is a generalized screening tool and does not directly measure body fat percentage. For individuals with high muscle density(athletes, bodybuilders), the scale often fails. Because muscle is roughly 18% denser than fat, highly fit individuals may be categorized as "Overweight" or "Obese" despite having athletic levels of body fat.

OFFICIAL SOURCEWorld Health Organization (WHO) Global DatabaseREF: 2026_METRIC_STANDARD