What is total daily energy expenditure (TDEE)?

Total daily energy expenditure is the energy burnt on average during an entire day. It reflects the average amount of energy spent during a typical day, but it is not the same each and every day. It is because our TDEE depends on many different factors, including:

Basal metabolism, which depends on many factors itself, including: age, sex, height, weight, fat free mass, fat mass. Depending on those factors, BMR represents 45 to 70 percent of TDEE.
Metabolic response of food, which is the energy needed to ingest and digest food. It is usually estimated to be 10% of total caloric intake.
Physical activity, which can vary every day. After BMR, this is the second-largest component of TDEE.
Physiological state: growth, pregnancy, lactation, etc.

Estimation of TDEE is usually undertaken by assessing your basal metabolic rate (BMR) and then multiplying it by the appropriate physical activity level (PAL). The physical activity level is a way to express a person's daily physical activity.

Choose which best applies to you and use it in the calculator;

little/no exercise (sedentary lifestyle): 1.2,
light exercise 1-2 times/week,: 1.375,
moderate exercise 2-3 times/week: 1.55,
hard exercise 4-5 times/week: 1.725,
physical job or hard exercise 6-7 times/week : 1.9,
professional athlete: 2.4.