BMR Calculator

How to Use This BMR Calculator

Our BMR (Basal Metabolic Rate) calculator determines how many calories your body burns at rest. Enter your age, gender, height, and weight to get your BMR using the scientifically-validated Mifflin-St Jeor equation. For enhanced accuracy, you can also input your body fat percentage to use the Katch-McArdle formula.

Select your activity level to calculate your Total Daily Energy Expenditure (TDEE), which represents the total calories you burn per day including physical activity. Set your primary goal (maintain, lose, or gain weight) and desired rate of change to get personalized calorie targets with detailed macronutrient breakdown.

Understanding Your Results

1. BMR (Basal Metabolic Rate) is the number of calories your body needs to perform basic physiological functions like breathing, circulation, and cell production while at complete rest. This represents about 60-75% of your total daily calorie burn.
2. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor that accounts for your exercise and daily movement. This represents the total calories you burn in a day and is used to determine maintenance calories.
3. Mifflin-St Jeor equation is currently considered the most accurate formula for calculating BMR in healthy individuals. It's more precise than the older Harris-Benedict equation, especially for overweight individuals.
4. Katch-McArdle formula is used when body fat percentage is known and can be more accurate for very lean or very muscular individuals since it's based on lean body mass rather than total weight.
5. Activity levels range from sedentary (1.2x BMR) for desk jobs with no exercise to extremely active (1.9x BMR) for athletes or people with physically demanding jobs plus daily intense training.
6. Calorie deficits and surpluses of 500 calories per day typically result in about 1 pound of weight change per week, since one pound of fat contains approximately 3,500 calories.
7. Macronutrient ratios shown are general recommendations (25% protein, 45% carbohydrates, 30% fats) but can be adjusted based on individual goals, dietary preferences, and medical conditions.
8. Minimum calorie intake should generally not go below 1,200 calories for women or 1,500 for men to ensure adequate nutrition and prevent metabolic slowdown, regardless of weight loss goals.
9. Individual variation in metabolism can be ±10-15% from calculated values due to factors like genetics, muscle mass, hormonal status, and metabolic adaptations from previous dieting.
10. Regular monitoring and adjustment of calorie intake based on actual weight changes and energy levels is recommended, as metabolic rate can change with weight loss, muscle gain, or changes in activity level.

Factors Affecting Metabolism

Age, gender, body composition, genetics, hormonal status, and previous dieting history all influence your metabolic rate. Muscle tissue burns more calories than fat tissue, which is why strength training can boost metabolism. Extreme calorie restriction can slow metabolism, making gradual changes more sustainable.

Using Your Results

Use your TDEE as a starting point for calorie planning. Track your weight and energy levels for 2-3 weeks, then adjust calories up or down by 100-200 per day as needed. Remember that sustainable weight changes happen gradually - aim for 0.5-2 pounds per week for best long-term results.