Resting Metabolic Rate (RMR) Calculator
Calculate how many calories your body burns just to stay alive at complete rest. Your RMR is the foundation for any accurate calorie budget for weight management.
Resting Metabolic Rate Guide
RMR vs BMR — The Difference
Basal Metabolic Rate (BMR) is the absolute minimum energy needed to maintain life — measured in a completely controlled environment (lying still for 12+ hours after an overnight fast in a thermoneutral room). Resting Metabolic Rate (RMR) is slightly higher — measured after a shorter fast in normal conditions. In practice, RMR is approximately 10-20% higher than strict BMR, and is the more useful practical figure. Both represent the energy burned without any activity. For a typical adult, RMR acc
Mifflin-St Jeor Formula
Male RMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. Female RMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. Example: 35-year-old male, 75kg, 175cm: RMR = (750) + (1093.75) − (175) + 5 = 1673.75 kcal/day. The Mifflin-St Jeor equation (1990) is consistently validated as the most accurate predictive formula for most people — outperforming the Harris-Benedict equation by approximately 10% in accuracy across diverse populations.
What Burns Your RMR Calories
The body's RMR is distributed roughly as: brain (20%), liver (20%), muscles at rest (20%), heart (9%), kidneys (8%), other organs (23%). Despite popular belief, your brain is one of the largest single consumers of resting energy — burning approximately 320-400 kcal/day regardless of how hard you are thinking. Muscle tissue burns approximately 13 kcal/kg/day at rest, compared to fat tissue at approximately 4.5 kcal/kg/day — this is the physiological basis for the claim that muscle increases metab
Factors That Change Your RMR
Increases RMR: higher muscle mass (each kg of muscle burns ~13 kcal/day at rest). Fever (each 1°C rise increases RMR by approximately 10%). Cold adaptation. Hyperthyroidism. Pregnancy. Decreases RMR: ageing (approximately 2% per decade after 20, largely due to muscle loss). Calorie restriction — 'metabolic adaptation' reduces RMR by 10-15% after prolonged dieting. Hypothyroidism. Menopause (modest reduction). Significant weight loss. Metabolic adaptation during dieting is why calorie deficits be
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