BMR Calculator
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Basal Metabolic Rate
Mifflin-St Jeor (Preferred)
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Harris-Benedict (Revised)
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Enter values to see the worked formula.
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Mifflin-St Jeor (1990) is the modern default and generally the most accurate for healthy adults. Harris-Benedict (revised 1984) is shown for comparison. Multiply BMR by an activity factor to get daily calorie needs. See also TDEE and calorie needs.
You enter your gender, age, height, and weight. The tool converts imperial units to metric if needed, then runs two formulas. Mifflin-St Jeor: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5 (male) or − 161 (female). Harris-Benedict (revised): uses slightly different coefficients and constants. The Mifflin-St Jeor result is then multiplied by five standard activity factors (1.2 to 1.9) to estimate total daily energy expenditure at each activity level.
Mifflin-St Jeor is generally recommended by the Academy of Nutrition and Dietetics as the most accurate for healthy, non-obese adults. Harris-Benedict is shown for comparison and tends to overestimate slightly. If the two differ significantly, Mifflin-St Jeor is typically the safer bet.
Be honest — most people overestimate their activity level. "Sedentary" covers a typical desk job with no structured exercise. "Lightly active" means light exercise 1–3 days per week. "Moderately active" is exercise 3–5 days per week. Only choose "very" or "extra" active if you train hard most days or have a physically demanding job.
Yes — your BMR is the floor below which you generally should not cut calories for extended periods. A typical approach is to eat at your TDEE (BMR × activity factor) minus 500 calories for about 1 pound of fat loss per week. Consult a dietitian for personalized guidance.
Both formulas subtract a factor for age because metabolic rate tends to decline as you get older, primarily due to loss of lean muscle mass. Strength training can help slow this decline by maintaining or building muscle.
Population-based formulas like these are typically within 10% of actual BMR for most healthy adults. Individual variation depends on lean body mass, genetics, hormones, and other factors. For precision, indirect calorimetry (a lab test) measures your actual resting metabolic rate.
Estimate only. Results reflect your inputs and standard formulas — they are not financial, tax, legal, health, or investment advice. Verify important decisions with a qualified professional.