Calculate Your RMR

A simple way to calculate your resting metabolic rate.






What is RMR?

RMR stands for Resting Metabolic Rate. It is the measure of energy you expend (or, calories you burn) while at rest. During the state of rest your body will only expend a sufficient amount of energy to maintain the basic functions of your body, such as: heart, lungs, nervous system, brain, liver, and other vital organs.

What is Activity-Adjusted RMR?

Your Activity-Adjusted RMR (McArdle at al 1996) is an estimated total expenditure of your body's energy in a single day, which is calculated using a factor to adjust your RMR for activity. Activities may include, but are not limited to: rest, walking, talking, working, exercise, and all movement you perform throughout the day. This estimate includes your "at rest" energy expenditure. It is the total estimated number of calories you burn in a 24-hour period (including rest and physical activity).


Your Activity-Adjusted RMR is:

Activity Level Description Calories Burned / Day
Sedentary Little or no exercise and desk job
Lightly Active Light exercise or sports 1-3 days a week
Moderately Active Moderate exercise or sports 3-5 days a week
Very Active Hard exercise or sports 6-7 days a week
Extremely Active Hard daily exercise or sports and physical job

What are the limits of the RMR calculator?

  1. The above calculator was developed by Mifflin, St Jeor, et al in a 1990 study published in the American Journal of Clinical Nutrition. It is utilizes an individual's weight, height, and age to estimate that person's Resting Metabolic Rate. However, when using weight as a variable, the equation ignores the make-up of fat to muscle. An individual with a higher percentage of muscle will burn more calories relative to a person - with the exact same weight - whose lean muscle mass is lower.

  2. The Mifflin - St. Jeor calculator is considered to be accurate within +/- 10% of actual results obtained in laboratory conditions. Therefore, an RMR result of 1500 may be an overestimate of 10% or an underestimate of 10%.
  3. When the Mifflin-St. Jeor calculator was used on non-obese individuals, 82% of the results were considered "accurate" (or within 10% of laboratory results). The results can be inaccurate as well:

    Overestimate of up to 15% (the 'Lower Boundary')
    Underestimate of up to 18% (the 'Upper Boundary')
  4. When the Mifflin-St. Jeor calculator was used on obese individuals, 70% of the results were considered "accurate" (or within 10% of laboratory results).

    Overestimate of up to 15%
    Underestimate of up to 20%
  5. Furthermore, this equation was developed using a 'sedentary' population of individuals. It may not be accurate for athletes who may carry a higher muscle mass.


  1. Mifflin, St Jeor et al (1990 Comparison of Predictive Equations for Resting Metabolic Rate in Healthy Nonobese and Obese Adults: A Systematic Review). "A new predictive equation for resting energy expenditure in healthy individuals". American Journal of Clinical Nutrition 51 (2): 241247. PMID 2305711
  2. McArdle, W.D., Katch, F.I., and Katch, V.L. 1996. Exercise physiology: energy, nutrition and human performance. 4th ed. Williams & Wilkins, Baltimore, Md.