Calorie Calculator

Your Basal Metabolic Rate is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulating blood, regulating body temperature, and maintaining organ function. BMR accounts for roughly 60-75% of your total daily energy expenditure.

Several factors influence your BMR, including your body composition (muscle burns more calories than fat at rest), age (BMR decreases with age), gender (men typically have higher BMRs due to greater muscle mass), and genetics. The Mifflin-St Jeor equation accounts for weight, height, age, and gender to provide an accurate BMR estimate.

Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor that accounts for physical movement throughout the day:

• Sedentary (x1.2): Desk job with little or no exercise. Most daily activities involve sitting.
• Lightly Active (x1.375): Light exercise or sports 1-3 days per week, or a job that involves some walking.
• Moderately Active (x1.55): Moderate exercise 3-5 days per week. This is the average for people who exercise regularly.
• Active (x1.725): Hard exercise 6-7 days per week, or a physically demanding job.
• Very Active (x1.9): Very intense daily exercise or training, or a highly physical job combined with exercise.

To lose weight, you need to consume fewer calories than your TDEE, creating a caloric deficit. A deficit of approximately 500 calories per day results in roughly 0.5 kg (1 pound) of weight loss per week, which is considered a safe and sustainable rate.

To gain weight or build muscle, you need a caloric surplus. An extra 250-500 calories per day above maintenance, combined with resistance training, supports lean muscle growth without excessive fat gain. Extreme deficits or surpluses are generally not recommended, as they can lead to muscle loss, nutritional deficiencies, or unwanted fat accumulation.

The Mifflin-St Jeor equation was developed in 1990 and has been validated by numerous studies as the most reliable predictive equation for estimating resting metabolic rate in healthy adults. It replaced the older Harris-Benedict equation (1919), which tends to overestimate calorie needs by about 5%.

While no formula is perfectly accurate for every individual, the Mifflin-St Jeor equation provides a strong starting point. Factors like body composition, hormonal conditions, and metabolic adaptation can cause individual variation. If you are not seeing expected results after several weeks, consider adjusting your intake by 100-200 calories.