Calorie Needs Calculator

Your daily calorie needs come down to two numbers: how much energy your body burns just existing, and how much more it burns because of what you do during the day. This calculator estimates the first number using the Mifflin-St Jeor equation, then scales it up based on your activity level to estimate the second.

That first number is your Basal Metabolic Rate, or BMR — the calories your body needs at complete rest to keep your heart beating, your organs running, and your temperature regulated. The Mifflin-St Jeor equation calculates it from your weight, height, age, and sex: 10 times your weight in kilograms, plus 6.25 times your height in centimeters, minus 5 times your age, with a final adjustment of +5 for men or -161 for women, reflecting typical differences in muscle mass and metabolic rate between sexes. It's widely considered one of the more accurate BMR formulas available, which is why it replaced the older Harris-Benedict equation in a lot of clinical and fitness settings.

BMR alone underestimates what most people actually burn in a day, since it doesn't account for movement, exercise, or even digestion. That's where the activity multiplier comes in: sedentary lifestyles multiply BMR by about 1.2, while very active ones can multiply it by 1.9 or more. Picking the activity level that honestly matches your week, rather than an aspirational one, matters a lot here, since the difference between "sedentary" and "very active" can easily be 700 or more calories a day.

The result is your estimated maintenance calories: roughly what you'd need to eat daily to keep your weight stable. Eating consistently below that number leads to weight loss over time, and eating above it leads to weight gain — though individual metabolism varies, so treat this as a starting point to adjust from, not a precise prescription.

If you've seen this same number called "TDEE" (Total Daily Energy Expenditure) elsewhere, that's the same calculation under a more technical name — see our TDEE calculator for the identical formula.