If you are unable to exercise, or just hate doing so, your body still burns calories to function and perform daily activities. How many calories you burn daily on average depends on your gender, age and size. Knowing your daily calorie burn can help you manage your weight and prevent unwanted weight gain.

Calorie Burn Even if you laid in bed all day, your body would burn a minimal number of calories. Your basal metabolic rate represents the calories your body uses to do basic functions, such as breathing and pumping blood, and accounts for about 60 to 75 percent of the total calories you burn every day. Another 10 percent of your daily calorie burn comes from the process of digesting, absorbing and transporting the nutrients you take in from the food you eat. The remaining calories you burn daily come from exercise and daily activity.

Factors Larger people burn more calories, on average, than smaller people. It takes more fuel to run a bigger engine. Men, due to their larger size, tend to burn more calories than women. Younger people usually burn more calories because they are often more active with daily activities, such as child care and housecleaning. Younger people also have a greater percentage of lean muscle mass, which is more metabolically active than fat mass. As you age, you naturally lose muscle mass -- especially if you don't perform regular strength training to prevent the loss.

Average Burn A primarily sedentary person is one who doesn't exercise and performs only the activities of daily life, such as showering, light chores and walking around the house or office. An adult man who is 5 feet 10 inches tall, weighs 154 pounds and is between 19 and 30 years old, burns about 2,400 to 2,600 calories daily. Between the ages of 31 to 50 years, this average man burns 2,200 to 2,400 calories daily and after age 51, between 2,000 and 2,200 calories daily. A woman who is 5 feet 4 inches tall and weighs 126 pounds burns 1,800 to 2,000 calories daily when between the ages of 19 and 30 years. From ages 31 to 50, this burn rate averages about 1,800 calories daily and decreases to 1,600 calories per day after age 51.