Educational tool — not a diagnosis. VivMetric calculators estimate body and fitness metrics using CDC, WHO, and NIH reference formulas. They do not provide medical advice, diagnosis, or treatment.
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BMR Calculator — US Units (lb/in)
Estimate your Basal Metabolic Rate with the Mifflin-St Jeor equation. Defaults to US imperial units for weight (lb) and height (in). Results update instantly as you type.
How the Mifflin-St Jeor Formula Works
Developed in 1990 and validated against indirect calorimetry measurements on 498 healthy subjects, the Mifflin-St Jeor equation is the most widely recommended predictive formula for basal metabolic rate. It estimates the kilocalories your body would burn per day at complete rest — awake, fasted 12 hours, in a thermoneutral environment, with minimal muscular effort.
Metric Form (original)
Male BMR = 10×kg + 6.25×cm − 5×age + 5
Female BMR = 10×kg + 6.25×cm − 5×age − 161
US Imperial Form (used by this calculator)
When you enter pounds and inches, the calculator converts internally to kg and cm (1 lb = 0.453592 kg; 1 in = 2.54 cm) then applies the original Mifflin-St Jeor equation, producing numerically identical results to metric inputs.
Result Interpretation
Your BMR represents the baseline energy required to sustain vital functions — breathing, circulation, organ function, and basic neural activity. In practice, your total daily calorie needs are always higher than BMR because of the thermic effect of food and physical activity. Multiplying BMR by standard activity factors (1.2 to 1.9) gives your Total Daily Energy Expenditure (TDEE). For healthy adults, Mifflin-St Jeor predictions typically fall within ±10% of measured indirect calorimetry values. Results for individuals outside the validation range (extreme ages, body compositions, or metabolic conditions) may have larger errors.
The next step after BMR is always TDEE. Head to our TDEE Calculator to see all five activity-factor rows at once, then check your BMI and body fat percentage to round out the picture. BMR alone is rarely actionable; combined with TDEE and body composition it becomes the backbone of a real calorie plan.