BMR & TDEE Calculator

What is Basal Metabolic Rate?

Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions like breathing, circulation, cell repair, and temperature regulation. It represents the largest component of your total daily energy expenditure, typically accounting for 60-75% of all calories burned. BMR is influenced by your weight, height, age, sex, and body composition.

BMR Calculation Formulas

Harris-Benedict Equation (Revised 1984)

• Men: 88.362 + (13.397 x weight kg) + (4.799 x height cm) - (5.677 x age)
• Women: 447.593 + (9.247 x weight kg) + (3.098 x height cm) - (4.330 x age)

Mifflin-St Jeor Equation (1990)

• Men: (10 x weight kg) + (6.25 x height cm) - (5 x age) + 5
• Women: (10 x weight kg) + (6.25 x height cm) - (5 x age) - 161

Average BMR by Age (kcal/day)

• Ages 20-29: Men ~1,750 / Women ~1,400
• Ages 30-39: Men ~1,700 / Women ~1,350
• Ages 40-49: Men ~1,650 / Women ~1,300
• Ages 50-59: Men ~1,550 / Women ~1,250
• Ages 60-69: Men ~1,450 / Women ~1,200

TDEE Activity Multipliers

• Sedentary (x1.2): Desk job, little or no exercise
• Lightly active (x1.375): Light exercise 1-3 days/week
• Moderately active (x1.55): Moderate exercise 3-5 days/week
• Very active (x1.725): Hard exercise 6-7 days/week
• Extra active (x1.9): Very intense exercise, physical job, or training twice daily

Calorie Strategy for Weight Management

Weight loss: Eat 300-500 calories below your TDEE for a healthy rate of about 0.5-1 lb per week. Muscle gain: Eat 300-500 calories above your TDEE combined with strength training and adequate protein (0.7-1.0 g per pound of body weight). Important: Never eat below your BMR for extended periods, as this triggers metabolic adaptation and makes long-term weight management harder.

Important Notes

BMR calculations are estimates with a margin of error of approximately 10%. Individual factors such as genetics, hormonal health, body composition, and medication can all affect your actual metabolic rate. For precise measurements, consider indirect calorimetry testing at a medical facility. Always consult a healthcare professional or registered dietitian before making significant changes to your diet.