RMR Calculator
Estimate your rmrcalculator with our free dietary calculator. See reference ranges, risk factors, and next-step guidance.
Formula
RMR = 10 x Weight(kg) + 6.25 x Height(cm) - 5 x Age + s
Where Weight is body mass in kilograms, Height is stature in centimeters, Age is in years, and s is +5 for males or -161 for females. This is the Mifflin-St Jeor equation, considered the most accurate RMR prediction formula. TDEE is then calculated by multiplying RMR by an activity factor.
Worked Examples
Example 1: Active Male RMR Calculation
Problem: A 30-year-old male weighing 80kg, 180cm tall, who exercises 3-5 days per week. What is his RMR and TDEE?
Solution: Mifflin-St Jeor (Male): RMR = 10(80) + 6.25(180) - 5(30) + 5\nRMR = 800 + 1125 - 150 + 5 = 1,780 cal/day\nActivity Factor (Moderately Active) = 1.55\nTDEE = 1,780 x 1.55 = 2,759 cal/day\nFor weight loss (-500 cal): 2,259 cal/day\nFor weight gain (+500 cal): 3,259 cal/day
Result: RMR: 1,780 cal/day | TDEE: 2,759 cal/day | Hourly burn: 74.2 cal/hr
Example 2: Sedentary Female RMR Calculation
Problem: A 45-year-old female weighing 65kg, 165cm tall, with a sedentary office job. Calculate RMR and daily calorie needs.
Solution: Mifflin-St Jeor (Female): RMR = 10(65) + 6.25(165) - 5(45) - 161\nRMR = 650 + 1031.25 - 225 - 161 = 1,295 cal/day\nActivity Factor (Sedentary) = 1.2\nTDEE = 1,295 x 1.2 = 1,554 cal/day\nMild deficit (-250): 1,304 cal/day\nModerate deficit (-500): 1,054 cal/day
Result: RMR: 1,295 cal/day | TDEE: 1,554 cal/day | Never eat below RMR for extended periods
Frequently Asked Questions
What is the difference between RMR and BMR?
Resting Metabolic Rate and Basal Metabolic Rate are closely related but measured under different conditions. BMR is measured under strict laboratory conditions after an overnight fast, complete physical rest, and in a thermoneutral environment, representing the absolute minimum energy your body needs to sustain vital functions like breathing and circulation. RMR is measured under less restrictive conditions and typically runs about 10 to 20 percent higher than BMR because it includes the energy cost of minor movements and recent food digestion. For practical purposes, RMR is more useful because it better represents your actual resting energy expenditure in real-world conditions rather than laboratory ideal conditions.
Why does RMR decrease with age?
RMR decreases approximately 1 to 2 percent per decade after age 20, primarily due to the progressive loss of metabolically active lean muscle tissue, a condition known as sarcopenia. Starting around age 30, adults lose approximately 3 to 8 percent of their muscle mass per decade, and since muscle tissue burns significantly more calories at rest than fat tissue, this loss directly reduces resting energy expenditure. Hormonal changes also contribute, including declining levels of growth hormone, testosterone, and thyroid hormones that regulate metabolic processes. Regular resistance training can significantly slow this decline by preserving and even building lean muscle mass, which is why strength training becomes increasingly important with age for maintaining metabolic health.
How accurate are RMR prediction equations?
RMR prediction equations like Mifflin-St Jeor are typically accurate to within plus or minus 10 percent of measured values for most individuals, which translates to roughly 150 to 200 calories per day for an average adult. However, accuracy decreases for certain populations including highly muscular athletes, very obese individuals, older adults over 70, and people of certain ethnic backgrounds due to differences in body composition not captured by height and weight alone. The gold standard for measuring RMR is indirect calorimetry, which measures oxygen consumption and carbon dioxide production to calculate actual energy expenditure. For most people, using a prediction equation and then adjusting based on real-world results over 2 to 4 weeks provides the best practical approach.
What is TDEE and how is it calculated from RMR?
Total Daily Energy Expenditure represents the total number of calories your body burns in a complete day, including all physical activity and the thermic effect of food. TDEE is calculated by multiplying your RMR by an activity factor that accounts for your typical daily movement and exercise patterns. The activity multipliers range from 1.2 for sedentary individuals who do little to no exercise, up to 1.9 for extremely active athletes training multiple hours daily. TDEE is the number you should use as your baseline for creating calorie targets, whether you want to lose weight by eating below it, maintain weight by matching it, or gain weight by exceeding it. Most adults have a TDEE between 1,800 and 3,000 calories per day.
Can I increase my RMR through lifestyle changes?
Yes, several evidence-based strategies can meaningfully increase your resting metabolic rate. The most effective approach is building lean muscle through resistance training, as each pound of muscle burns approximately 6 to 7 calories per day at rest compared to only 2 calories per pound of fat. High-intensity interval training has been shown to elevate RMR for up to 48 hours after exercise through a phenomenon called excess post-exercise oxygen consumption. Adequate protein intake of 0.7 to 1 gram per pound of body weight supports muscle maintenance and has a higher thermic effect than carbohydrates or fats. Avoiding prolonged severe calorie restriction is also important because extended dieting below RMR can trigger metabolic adaptation, slowing your metabolism by 15 to 25 percent beyond what weight loss alone would predict.
How does body composition affect RMR more than body weight?
Two people of identical height, weight, age, and sex can have dramatically different RMR values based on their body composition, specifically their ratio of lean mass to fat mass. Muscle tissue is metabolically active, requiring constant energy for protein synthesis, ion transport, and cellular maintenance, burning approximately 6 to 7 calories per pound per day at rest. Fat tissue is comparatively inactive, burning only about 2 calories per pound per day. This means a 180-pound person with 15 percent body fat could have an RMR 200 to 300 calories higher than a 180-pound person with 30 percent body fat. This is why the Katch-McArdle equation, which uses lean body mass, can be more accurate for athletic individuals than equations based solely on total body weight.