BMR Calculator
Calculate your Basal Metabolic Rate using the Mifflin-St Jeor equation. Supports metric (kg/cm) and imperial (lb/in) units. Runs entirely in your browser.
This calculator is for informational purposes only and does not constitute medical advice.
What is BMR and how is it calculated?
Basal Metabolic Rate is the number of calories your body needs to sustain basic physiological functions — breathing, circulation, and cell production — at complete rest. This calculator uses the Mifflin-St Jeor equation, currently the most accurate formula for most adults: 10W + 6.25H − 5A + 5 for men and 10W + 6.25H − 5A − 161 for women (W = weight in kg, H = height in cm, A = age in years). Imperial inputs are converted to metric before applying the formula. All computation happens locally in your browser.
BMR is not the same as the number of calories you should eat — it is the floor. Your actual daily needs are BMR multiplied by an activity factor, which gives your Total Daily Energy Expenditure (TDEE). Use the TDEE calculator on this site for a more actionable calorie target.
FAQ
Why does my BMR decrease with age? Lean muscle mass declines with age, reducing the metabolic demand of resting tissue. The Mifflin-St Jeor equation accounts for this with the age term.
Is BMR the same as RMR? They are similar but not identical. RMR (Resting Metabolic Rate) is measured under slightly less strict conditions and is typically 10–20% higher than true BMR. For practical diet planning the two are interchangeable.