Calculate your basal metabolic rate and total daily calorie needs
This tool calculates your Basal Metabolic Rate and Total Daily Energy Expenditure, the two foundational calorie numbers behind any nutrition plan. BMR is the energy your body burns at complete rest, while TDEE multiplies BMR by an activity factor to estimate real-world daily calorie needs. This calculator runs both the Mifflin-St Jeor and Harris-Benedict formulas and averages them for a more balanced result.
BMR starts from your weight, height, age, and sex. The Mifflin-St Jeor equation for men is 10 times weight in kg, plus 6.25 times height in cm, minus 5 times age, plus 5. For women it is the same but minus 161 instead of plus 5. Harris-Benedict follows the same shape with slightly different coefficients. Once you have BMR, TDEE equals BMR times an activity factor: about 1.2 for sedentary, 1.375 for light activity, 1.55 for moderate, 1.725 for very active, and higher for extreme training. In plain terms, BMR is your resting burn and the activity factor scales it up to reflect how much you move.
Take a 30 year old man who is 180 cm / 5 ft 11 in and 80 kg / 176 lb. Using Mifflin-St Jeor: 10 times 80 is 800, plus 6.25 times 180 is 1,125, minus 5 times 30 is 150, plus 5. That gives 800 plus 1,125 minus 150 plus 5, which is 1,780 calories per day at rest. If he is moderately active, TDEE is 1,780 times 1.55, or about 2,759 calories per day. To lose fat gradually he might eat around 2,300 to 2,450, and to gain steadily he might eat around 3,050 to 3,250.
Select your sex and enter your age, weight, and height. Toggle between pounds and kilograms and between inches and centimeters as needed. Choose your activity level from five options ranging from Sedentary to Very Active. The calculator returns your BMR, your TDEE, and calorie targets for five goals: aggressive loss, moderate loss, maintenance, moderate gain, and aggressive gain.
TDEE is an estimate, and real metabolisms vary. The formulas assume an average body composition, so very muscular or very lean people may burn more or less than predicted. Activity factors are broad buckets that rarely match daily life exactly, and appetite, sleep, and stress all influence real intake and output. Use your calculated number as a starting point, then adjust based on how your weight actually trends over two to four weeks. Consult a physician or registered dietitian before major changes.
What is a good starting calorie target? Maintenance TDEE is the neutral baseline. Subtract roughly 300 to 500 calories for gradual fat loss, or add a similar amount for steady muscle gain.
Why do the two formulas give different numbers? Mifflin-St Jeor and Harris-Benedict use slightly different coefficients. Averaging them reduces the error from relying on either formula alone.
How do I pick an activity level? Be honest about structured exercise and daily movement combined. Most people who train a few times a week fall into light to moderate rather than very active.
How often should I recalculate? Recalculate after a meaningful change in weight or activity, and adjust your intake based on real-world results rather than the formula alone.