**Introduction to Calorie Calculator:**

A calorie calculator is a tool used to estimate the number of calories a person needs to consume each day to maintain, gain, or lose weight based on various factors such as age, gender, weight, height, activity level, and goals. It provides valuable insight into an individual’s energy expenditure and helps in creating a balanced diet plan.

**Components of Calorie Calculator:**

**Basal Metabolic Rate (BMR):**

This is the number of calories your body needs at rest to maintain vital functions like breathing and circulation. The Harris-Benedict equation is commonly used to calculate BMR.

**Harris-Benedict Equation for BMR (Revised by Roza and Shizgal):**For Men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) – (5.677 × age in years)For Women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) – (4.330 × age in years)

**Physical Activity Level (PAL):**

It involves considering daily activities and exercise to determine total energy expenditure (TEE). PAL is multiplied by BMR to estimate total daily calorie needs.

**Total Daily Energy Expenditure (TDEE):**

TDEE represents the total calories burned in a day, combining BMR with the calories expended through physical activity.

**Formula for Calorie Calculator:**

TDEE = BMR × PAL

**Summary:**

A calorie calculator employs the Harris-Benedict equation or other formulas to estimate Basal Metabolic Rate (BMR). Then, it factors in the Physical Activity Level (PAL) to determine Total Daily Energy Expenditure (TDEE). This TDEE value helps individuals in managing their calorie intake to achieve specific health goals like weight maintenance, weight gain, or weight loss.