Basal Metabolic Rate (BMR) and  Resting Metabolic Rate (RMR)  are estimates of how many calories your body needs if you were to do nothing.An accurate BMR is measured under very restrictive circumstances when a person is awake, but at complete rest, it requires that the person's sympathetic nervous system not be stimulated.A more common and closely related measurement, used under less strict conditions, is

RMR. RMR and BMR are similar and yield extremely similar results. We can estimate the value of BMR/RMR using a same formula.

Calculating BMR and RMR

To calculate the number of calories you burn in a day while at rest, you can work out the Harris Benedict formula or The Mufflin equation for your own height, weight.

The Harris-Benedict formula
For men: BMR = 66+(13.7× weight in kg)+(5×height in cm) – (6.8×age in years)
For women: BMR = 655+(9.6×weight in kg)+(1.8×height in cm)–(4.7×age in years)

The Mufflin equation
For men: RMR=(10×weight in kg)+(6.25×height in cm)-(5×age in years) + 5
For women: RMR=(10×weight in kg)+(6.25×height in cm)-(5×age in years) - 161

 A more accurate formula is the Katch-McArdle formula based on lean body mass:

The Katch-McArdle formula
BMR/RMR(men and women)=370+(21.6*lean body weight in kg)

Pay attention that you need to convert your weight from pounds to kilograms, and convert convert your height from inches to centimeters.