Free BMI and calorie target calculator. Compute your Body Mass Index (kg/m^2 from metric or imperial) and your daily calorie needs with the Mifflin-St Jeor BMR formula, then adjust for lose, maintain or gain goals.
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Enter your details above and press Calculate.
How bmi & calorie target calculator works
This tool computes your Body Mass Index (BMI) and your daily calorie target in one step. Enter your height and weight (metric in cm/kg or imperial in feet, inches and pounds), your sex, age, activity level and goal. BMI is calculated as weight in kilograms divided by height in metres squared (kg/m^2) and sorted into the standard Underweight, Normal weight, Overweight and Obese categories.
Your daily calorie target uses the Mifflin-St Jeor resting metabolic rate (BMR) formula, which estimates the energy your body burns at rest: for men BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5, and for women BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161. This BMR is multiplied by an activity factor (1.2 for sedentary up to 1.9 for very active) to get your Total Daily Energy Expenditure (TDEE) - the calories you need to maintain your current weight.
Your goal then shifts the target: lose weight applies a 500 kcal/day deficit (about 1 lb/week), gain weight applies a 500 kcal/day surplus, and maintain keeps your TDEE as-is. The tool also shows the healthy weight range for your height (BMI 18.5-24.9). Everything runs in your browser with no data sent anywhere. These estimates are for healthy adults and are not medical advice - athletes, pregnant or breastfeeding people, and anyone with a medical condition should consult a professional.
Frequently asked questions
What is BMI and how is it calculated?
BMI (Body Mass Index) is weight in kilograms divided by height in metres squared (kg/m^2). It gives a rough screen of whether your weight is in a healthy range for your height. The standard categories are Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25-29.9) and Obese (30 and above). BMI does not distinguish muscle from fat, so very muscular people can read high without being unhealthy.
What is the Mifflin-St Jeor formula?
The Mifflin-St Jeor equation estimates your Basal Metabolic Rate (BMR) - the calories your body burns at rest. For men it is 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5, and for women it is 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161. It is widely considered the most accurate predictive formula for healthy adults. Your BMR is multiplied by an activity factor to get your Total Daily Energy Expenditure (TDEE).
How does the lose, maintain or gain goal work?
Maintain keeps your calorie target equal to your TDEE. Lose weight subtracts about 500 kcal/day, which works out to roughly one pound of body fat per week (a pound of fat stores about 3500 kcal). Gain weight adds about 500 kcal/day for a similar rate of weight gain. A safe rate of change is 0.5-1 lb per week; faster changes are harder to sustain and may lose muscle along with fat.
Are these calorie numbers accurate for everyone?
No. These are population-average estimates for healthy adults. They do not account for body composition, genetics, medical conditions, pregnancy, breastfeeding, or many medications. Use the result as a starting point, track your actual weight trend over a few weeks, and adjust your intake up or down based on what the scale does. For personalised advice consult a registered dietitian or doctor.
