Resting Metabolic Rate Calculator Please Enter Your:     Height: ' " Weight: Age: Gender: Male Female     Your RMR is (click GO)... Calories How many calories does your body use when you're doing absolutely nothing? Your Resting Metabolic Rate (RMR) is the minimum number of calories your body needs to support its basic physiological functions, including breathing, circulating blood and all of the numerous biochemical reactions required to keep you alive. Your RMR is generally 60-75% of your total daily caloric expenditure. Knowing the minimum number of calories your body needs is important if you're trying to lose, gain or maintain your current weight. To calculate the number of calories your body uses during an average day by applying an activity level ... try our Daily Calorie Needs calculator. .