Estimate your daily calorie needs to maintain, lose, or gain weight, based on your activity level.
This uses the Mifflin-St Jeor equation to estimate your basal metabolic rate (BMR) — the calories your body burns at rest — then multiplies it by an activity factor to estimate your total daily energy expenditure (TDEE). A pound of body weight is roughly 3,500 calories, so the loss/gain estimates adjust your maintenance number up or down accordingly.
This is a helpful starting estimate, not a medical calculation — actual needs vary by individual metabolism, body composition, and health conditions.
Enter your age, sex, height, weight, and activity level. Click Calculate, and the tool returns your estimated maintenance calories (the amount needed to keep your current weight stable), along with adjusted figures for moderate weight loss and weight gain. These adjusted numbers apply a calorie deficit or surplus around your maintenance level, giving you a practical starting point for setting a daily calorie target based on your goal.
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest just to maintain basic functions — breathing, circulation, cell production, and organ function. It doesn't include any calories burned through movement or digestion. Total Daily Energy Expenditure (TDEE) builds on BMR by adding in calories burned through daily activity, exercise, and the energy used to digest food. TDEE is the more useful number for everyday calorie planning, since it reflects your actual total energy needs rather than just your body's baseline resting requirement.
This calculator uses the Mifflin-St Jeor equation, widely regarded by nutrition researchers as one of the more accurate BMR formulas for most adults, having generally outperformed older formulas like Harris-Benedict in validation studies. For men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) + 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age(years) − 161. The activity multiplier is then applied on top of this baseline — ranging roughly from 1.2 for sedentary lifestyles to 1.9 for very physically demanding jobs or heavy daily training, depending on the calculator's specific scale.
Two people with identical age, height, and weight can have very different calorie needs depending on how active they are day to day. A sedentary office worker and a construction worker of the same body stats might have a calorie need difference of 500-800 calories per day or more, simply due to activity level. This is why accurately estimating your activity level — rather than defaulting to "sedentary" or overestimating how active you actually are — matters significantly for getting a useful, realistic calorie target rather than one that's off by a substantial margin.
The commonly cited rule that a pound of body weight equals roughly 3,500 calories is a useful rough approximation, not an exact biological constant. It works reasonably well for estimating a moderate calorie deficit or surplus over time, but actual weight change is influenced by many factors beyond simple calorie math — water retention, muscle gain or loss, hormonal changes, and metabolic adaptation (where the body's calorie needs can shift somewhat in response to sustained changes in intake) all play a role. This is why weight loss or gain often doesn't track perfectly linearly with the math, especially over longer periods.
A calorie target tells you how much energy to consume, but how those calories are split between protein, carbohydrates, and fat also matters for how a diet feels and performs, especially during weight loss. Higher protein intake is commonly recommended during a calorie deficit, since it helps preserve muscle mass while losing weight and tends to support satiety better than an equivalent amount of carbs or fat. There's no single "correct" macronutrient split that works for everyone — individual preferences, activity type, and how satisfied a particular ratio makes someone feel all play a role in finding a sustainable approach within a given calorie target.
Why might my actual weight change differ from this calculator's prediction? Individual metabolism varies, and factors like water retention, muscle changes, sleep, stress, and hormonal fluctuations all influence weight independent of pure calorie math. Use the estimate as a starting point, then adjust based on your real-world results over a few weeks.
Is a bigger calorie deficit always better for faster weight loss? Not necessarily — very large deficits can be harder to sustain, may increase muscle loss alongside fat loss, and can trigger metabolic adaptation. A moderate, sustainable deficit is generally recommended over an aggressive one.
Does this calculator account for medical conditions affecting metabolism? No — conditions like thyroid disorders can significantly affect metabolic rate. If you have a diagnosed condition affecting metabolism, work with a healthcare provider for personalized calorie guidance rather than relying solely on this estimate.
How often should I recalculate my calorie needs? Recalculating every few weeks, or after a meaningful weight change (5+ lbs) or activity level change, keeps the estimate reasonably aligned with your current body and lifestyle.
Should I eat back the calories I burn through exercise? This calculator's activity multiplier already factors in general activity level, so separately adding back workout calories on top can lead to overestimating your total needs.
Do I need to recalculate as I lose or gain weight? Yes — since the formula uses your current weight, recalculating periodically as your weight changes keeps the maintenance estimate reasonably accurate over time.
Why do two calorie calculators sometimes give different results for the same inputs? Different formulas (Mifflin-St Jeor vs. Harris-Benedict, for example) and different activity multiplier scales can produce modestly different estimates for identical inputs.
Is this calculator suitable for children or teenagers? No — it's designed for adults. Children and teens have different growth-related energy needs that adult calorie formulas don't account for accurately.
Last reviewed by Mehmed on July 11, 2026.