The number of calories an average person burns depends on various factors such as their age, weight, height, and daily activities. An estimation of the average number of calories burned per day can be made using the Basal Metabolic Rate (BMR) formula. BMR is the amount of energy (calories) an individual needs to maintain basic body functions like breathing, circulation, and temperature regulation.

The Basal Metabolic Rate (BMR) is the number of calories a person burns at rest to maintain basic life functions such as breathing, circulating blood, and maintaining body temperature. BMR accounts for 60 to 75 percent of the total calories burned in a day and is determined by factors such as age, weight, and height.

Physical activity is another major factor that affects the number of calories a person burns. The more active a person is, the more calories they will burn. Some common forms of physical activity include exercise, sports, household chores, and work-related activities. The intensity, duration, and type of physical activity all play a role in determining how many calories are burned.

The average sedentary adult burns about 1,500 to 1,800 calories a day. However, if they increase their physical activity level, they can burn up to 2,000 to 2,500 calories a day. For example, a person who weighs 150 pounds and runs for 30 minutes at a moderate pace can burn about 300 calories.

Body weight also plays a role in the number of calories burned. Generally, the heavier a person is, the more calories they will burn. This is because it takes more energy to move a heavier body. However, muscle mass also affects calorie burning, as muscle tissue burns more calories than fat tissue. So, even if two people have the same body weight, the person with more muscle will burn more calories.

Age is another factor that affects calorie burning. As a person ages, their BMR decreases, meaning they burn fewer calories at rest. This is why it is important for older adults to stay physically active to maintain their calorie-burning potential.

It is important to note that the above-mentioned calculations are only estimates and may not be accurate for every individual. The number of calories burned can also vary based on other factors such as metabolism, genetics, and overall health.

Physical activities like exercise, sports, and household chores can also significantly impact the number of calories burned. For example, a 30-minute walk at a moderate pace can burn approximately 150-300 calories, while a 30-minute run can burn up to 400 calories. A vigorous workout session at the gym can burn even more calories.

The number of calories burned while performing household chores also varies based on the type of activity and intensity level. For example, vacuuming for 30 minutes can burn around 100 calories, while mopping the floor for the same amount of time can burn approximately 120 calories.

In addition to BMR and physical activity, the thermic effect of food (TEF) also affects the number of calories a person burns. TEF refers to the energy required to digest and process food. It is estimated that about 10 percent of the total calories burned in a day are used for the TEF.

In conclusion, the number of calories a person burns in a day varies depending on several factors including BMR, physical activity, body weight, age, and the thermic effect of food. On average, an adult burns about 1,500 to 2,000 calories a day, but this can vary based on individual factors and lifestyle. To maintain a healthy weight, it is important to balance the number of calories consumed with the number of calories burned through physical activity.