Calculateus

Calorie Calculator

Estimate your daily calorie needs to maintain, lose or gain weight.

Sex
Units

Result

Maintain Weight
2,573 cal/day
Mild Weight Loss (-10%)
2,316 cal/day
Weight Loss (-20%)
2,059 cal/day
Mild Weight Gain (+10%)
2,831 cal/day
Basal Metabolic Rate
1,660 cal/day
4K3K2K1K0Calories/day: 2KCalories/day: 2KCalories/day: 2KCalories/day: 3KCalories/day: 3KBMRLoss (-20%)Mild Loss (-10%)MaintainMild Gain (+10%)

About the Calorie Calculator

Whether your goal is to lose weight, gain weight, or simply maintain where you are, it starts with knowing how many calories your body actually needs. Our Calorie Calculator estimates your daily calorie needs using your age, sex, height, weight, and activity level, then shows targets for maintenance, mild loss, more aggressive loss, and mild gain.

How It Works

The calculator first estimates your Basal Metabolic Rate (BMR) - the calories your body burns at complete rest - using the Mifflin-St Jeor equation, which is considered one of the more accurate formulas available. It then multiplies that by an activity multiplier ranging from sedentary to athlete to estimate your Total Daily Energy Expenditure (TDEE), the number of calories you burn in an average day.

Men: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 Women: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161 TDEE = BMR × activity multiplier

Formula & Methodology

Mifflin-St Jeor was published in 1990 and validated against measured resting metabolic rate in a much larger, more diverse sample than the older Harris-Benedict equation it's gradually replaced - that's why it's now the equation most dietitians and the Academy of Nutrition and Dietetics recommend. Weight, height, and age each carry a coefficient reflecting how strongly they predict metabolic rate, and the sex-specific constant (+5 for men, −161 for women) adjusts for average differences in body composition between sexes at the same weight and height.

Step-by-Step: Calculating It By Hand

  1. 1Convert weight to kilograms and height to centimeters if needed.
  2. 2Multiply weight by 10 and height by 6.25, then add them together.
  3. 3Subtract 5 times age, then add 5 (men) or subtract 161 (women) for BMR.
  4. 4Multiply BMR by an activity multiplier (roughly 1.2 to 1.9) to estimate total daily calorie needs.

Examples

Moderately active

A 30-year-old man, 5'8", 180 lb, with moderate exercise has a TDEE of roughly 2,750 calories/day to maintain his current weight.

Weight loss target

The same person aiming for steady weight loss would target around 2,200 calories/day - a 20% deficit - for the 'weight loss' option shown by the calculator.

Advantages

  • Uses the Mifflin-St Jeor equation, widely regarded as one of the more accurate BMR formulas
  • Shows multiple targets (maintain, mild loss, loss, mild gain) instead of just one number
  • Adjusts for five different activity levels
  • Free to recalculate anytime your weight or activity changes

Common Mistakes

  • Overestimating activity level, which inflates the calorie target
  • Not adjusting the target as your weight changes over weeks or months
  • Treating the number as exact rather than a solid starting estimate
  • Ignoring that very low-calorie targets can be unsustainable or unhealthy without guidance

Edge Cases to Watch For

  • This formula was developed and validated primarily in adults of average body composition - it tends to be less accurate for people who are very muscular or have unusually high or low body fat.
  • BMR naturally declines with age even at a constant weight, which is why the formula subtracts a term proportional to age.
  • Extremely low-calorie diets can temporarily suppress metabolic rate below what this formula predicts, a phenomenon sometimes called adaptive thermogenesis.
  • This estimates typical adults - it isn't validated for pregnant or breastfeeding individuals, who have different metabolic demands entirely.

Common Use Cases

  • Setting a daily calorie target for weight loss or gain
  • Understanding maintenance calories before starting a diet plan
  • Adjusting nutrition goals after a change in activity level
  • Pairing with a macro plan for more detailed nutrition tracking
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

How many calories should I eat to lose weight?

A deficit of about 500 calories/day below your maintenance level typically produces roughly 1 lb of weight loss per week. This calculator's -10% and -20% figures give you a mild and moderate deficit to choose from.

What's the difference between BMR and TDEE?

BMR is the calories you'd burn at complete rest. TDEE adds your activity level on top of BMR, giving your actual maintenance calories for a normal day.

Related calculators

BMI CalculatorCalculate your Body Mass Index (BMI) and see which weight category you fall into.BMI Prime CalculatorCalculate BMI Prime - the ratio of your BMI to the upper limit of normal BMI (25).BMR CalculatorCalculate your Basal Metabolic Rate - calories burned at complete rest.TDEE CalculatorCalculate your Total Daily Energy Expenditure based on activity level.

Related articles

What a Realistic Weight Loss Timeline Actually Looks LikeWeight loss apps often show a straight-line prediction, but real progress isn't linear. Here's how to calculate a realistic timeline and why it bends.How Big Should Your Calorie Deficit Actually Be?Too aggressive a deficit backfires. Here's how to calculate a calorie deficit that matches a realistic, sustainable weight loss rate.Why Waking Up Mid-Sleep-Cycle Makes You Feel WorseSleep happens in roughly 90-minute cycles, and waking up in the middle of one feels far worse than waking at the end. Here's the math behind bedtime planning.

Conclusion

Calorie needs are individual and change over time, so treat this as a well-informed starting point rather than a fixed rule. Track your results over a few weeks and adjust as needed - and check out our Macro and TDEE calculators for more detailed nutrition planning.

References