Calorie Calculator

Understanding how many calories your body needs each day is the foundation of any effective nutrition or fitness plan. Whether your goal is weight loss, muscle gain, or simply maintaining your current physique, eating the right amount of energy — not too much, not too little — makes the difference between seeing results and spinning your wheels. Our free Calorie Calculator uses the Mifflin-St Jeor equation, widely recognized by nutritionists and researchers as the most accurate formula for estimating Basal Metabolic Rate (BMR), to compute the calories your body burns at complete rest. This BMR is then multiplied by your selected activity level to produce your Total Daily Energy Expenditure (TDEE) — the actual number of calories you burn in a typical day including all movement, exercise, and daily activities. From there, the calculator generates six personalized daily calorie targets: maintenance (your TDEE), mild weight loss (TDEE minus 250 calories for approximately half a pound per week), standard weight loss (minus 500 calories for about one pound per week), aggressive weight loss (minus up to 1000 calories, with a minimum floor of 1200 to ensure adequate nutrition), and two weight gain tiers for those looking to build muscle or recover from being underweight. Your Body Mass Index (BMI) is also computed and categorized to provide additional context about your current weight status.

How BMR and TDEE Are Calculated

The Mifflin-St Jeor equation, developed in 1990 and validated across multiple population studies, is considered the gold standard for BMR estimation, outperforming the older Harris-Benedict equation in accuracy. For men, BMR is calculated as (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5. For women, the formula uses (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161. The gender difference accounts for the fact that women typically have a higher percentage of body fat and lower lean muscle mass at the same weight, which results in a slightly lower resting metabolic rate. Once BMR is established, it is multiplied by an activity factor: 1.2 for sedentary lifestyles (desk job, little exercise), 1.375 for light activity (exercise 1–3 times weekly), 1.55 for moderate activity (3–5 days per week), 1.725 for very active individuals (intense exercise 6–7 days weekly), and 1.9 for extremely active people with physically demanding jobs and daily training schedules. The resulting TDEE represents your maintenance calories — eating this amount should theoretically keep your weight stable over time. Creating a deficit of 500 calories per day below TDEE results in approximately one pound of fat loss per week, while a surplus of 500 calories per day above TDEE supports approximately one pound of muscle gain per week when combined with proper strength training and adequate protein intake.

How to Use the Calorie Calculator

1. Choose your unit system — Toggle between Metric (kilograms and centimeters) or Imperial (pounds, feet, and inches) based on your preference. All calculations are performed using the same underlying formulas regardless of which input system you choose.
2. Enter your personal metrics — Provide your age, gender, weight, and height. These four factors are the primary determinants of your basal metabolic rate according to the Mifflin-St Jeor equation.
3. Select your activity level — Choose the option that best describes your typical weekly physical activity. Be honest — overestimating your activity level is a common reason people fail to see expected weight loss results. If you are unsure between two levels, choose the lower one for a more conservative calorie estimate.
4. Read your calorie targets — Your BMR and TDEE display prominently at the top. Below them, six calorie targets give you clear numbers for every goal: maintain, lose weight at three intensities, and gain weight at two levels. Choose the target that aligns with your current fitness objective and track your food intake to stay within that daily range.