RMR Calculator (Resting Metabolic Rate). Enter your age, sex, height, and weight to calculate your Resting Metabolic Rate (RMR) — the number of calories your body burns at complete rest each day. Your RMR result is calculated using the Harris-Benedict formula, and you'll also see estimated daily calorie needs based on your activity level. Also try the BMR Calculator (Basal Metabolic Rate).
RMR is the number of calories your body burns while completely at rest — the energy required to maintain basic life functions like breathing, circulation, cell production, and temperature regulation. It accounts for roughly 60–70% of your total daily energy expenditure. See also our Katch-McArdle Calculator.
BMR (Basal Metabolic Rate) is measured under very strict conditions — after 12 hours of fasting and complete rest in a controlled environment. RMR is slightly less strict and is typically measured after just a few hours of rest, making it more practical and slightly higher than BMR. In everyday use, the two terms are often used interchangeably.
This depends on your age, sex, height, and weight. For a 30-year-old male weighing 80 kg and standing 180 cm tall, the RMR is approximately 2,050 calories per day. Use this calculator to get a personalized estimate based on your own measurements.
Several factors influence RMR, including age (it decreases with age), sex (males generally have a higher RMR), body composition (more muscle mass increases RMR), genetics, hormonal levels (especially thyroid hormones), environmental temperature, and prolonged dieting or caloric restriction.
Once you know your RMR and apply an activity multiplier to find your Total Daily Energy Expenditure (TDEE), you can create a calorie deficit to lose weight. A common approach is to consume 500 fewer calories per day than your TDEE, which typically results in about 0.5 kg (1 lb) of weight loss per week.
To gain muscle, you need to eat in a calorie surplus above your TDEE. Adding approximately 250–500 calories per day above your maintenance level, combined with a strength training program, supports muscle growth while minimizing excess fat gain.
Yes. Prolonged caloric restriction or extended fasting can reduce your RMR as your body adapts to conserve energy — a phenomenon known as metabolic adaptation. Preserving lean muscle mass through resistance training and avoiding excessively low calorie intakes can help mitigate this effect.
Formula-based RMR calculators like this one provide a good estimate for most people, but individual results can vary due to genetics, body composition, and health conditions. For a precise measurement, a clinical indirect calorimetry test performed by a healthcare professional is the gold standard.