Calorie Calculator
Estimate your daily calorie needs and weight loss or gain targets using the Mifflin-St Jeor equation — the most accurate formula for the general population.
How to use this calorie calculator
- Enter your sex, age, current weight, and height accurately.
- Select the activity level that honestly describes your typical week — most people overestimate this.
- Maintenance calories (TDEE) is what you eat to stay the same weight.
- To lose 1 lb per week, eat 500 calories below maintenance daily.
- Track actual intake for 2 weeks and adjust — individual metabolism varies from estimates by 10–15%.
Formula
Mifflin-St Jeor: Men BMR = 10×kg + 6.25×cm − 5×age + 5. Women = 10×kg + 6.25×cm − 5×age − 161. TDEE = BMR × activity factor (1.2–1.9).
About the Calorie Calculator
Calorie counting is the most evidence-based approach to weight management available, but it works best when understood as an estimation tool rather than precise measurement. Food calorie labels have a legal tolerance of ±20%, and cooking methods affect calorie absorption. Despite these imprecisions, calorie awareness consistently produces better outcomes than intuitive eating alone for specific weight goals. The critical insight of energy balance — calories in versus calories out — is correct but oversimplified. Both sides of the equation are dynamic. When you eat less, your body adapts by reducing TDEE through multiple mechanisms: decreased body temperature, reduced spontaneous movement (NEAT drops), lower thyroid output, and hormonal changes that increase hunger. This metabolic adaptation is why weight loss slows after the first few weeks despite consistent deficit. Brief diet breaks at maintenance calories can partially reset these adaptations. For practical implementation, focusing on food quality alongside quantity typically produces better results than restriction alone. A diet providing 30% of calories from protein, rich in whole foods and fiber, with minimal ultra-processed food supports greater satiety per calorie, better muscle retention during deficit, and improved long-term adherence compared to equivalent calories from lower-quality sources. The most important variable in any calorie-based approach is tracking accuracy. A food scale is substantially more accurate than eyeballing portions — studies show visual portion estimation leads to errors of 30–50% for energy-dense foods. Apps like MyFitnessPal, Cronometer, and Lose It make consistent tracking feasible. Even imperfect tracking creates behavioral awareness that improves food choices — often more valuable than the precise calorie count itself.
Frequently asked questions
+What is TDEE and why does it matter more than BMR?
BMR (Basal Metabolic Rate) is calories burned at complete rest — breathing, circulation, and cell maintenance. It is 60–75% of total daily calorie burn. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor to account for movement, exercise, and digestion. TDEE is the number that actually matters for weight management — it is the amount you can eat while maintaining your current weight. Eating below TDEE creates a deficit and drives weight loss; eating above TDEE creates a surplus for weight gain or muscle building.
+Why am I not losing weight eating below my calculated calorie target?
Several factors cause apparent resistance to calorie deficit. First, tracking error — studies show people underreport food intake by 20–50%, even when trying. Liquid calories (sauces, oils, drinks) are frequently missed. Second, the activity factor may be overestimated — most office workers should use 1.2–1.375, not 1.55. Third, metabolic adaptation — extended restriction reduces TDEE through reduced spontaneous movement, lower body temperature, and hormonal changes. After 4+ weeks in deficit, recalculate TDEE at your new weight. Fourth, water retention from sodium, strength training inflammation, or hormonal cycles can mask fat loss on the scale for 1–3 weeks.
+How many calories should I eat to lose weight safely?
Safe weight loss is 0.5–1.5% of body weight per week. The recommended maximum sustained deficit is 1,000 calories/day (approximately 2 lbs/week loss). More aggressive deficits risk muscle loss, nutritional deficiency, and metabolic adaptation. The minimum safe intake for most adults is 1,200 calories for women and 1,500 for men. Slower rates (0.5–1 lb/week) are associated with better long-term maintenance and significantly less muscle loss compared to aggressive restriction.
+Do calories from all foods count the same?
All calories contribute equally to energy balance mathematically, but different macronutrients affect appetite and metabolic rate differently. Protein has the highest thermic effect — approximately 25–30% of protein calories are burned during digestion, versus 6–8% for carbohydrates and 2–3% for fat. Protein is also the most satiating macronutrient per calorie and the most effective for preserving muscle during weight loss. High-fiber whole foods increase satiety and slow digestion. Ultra-processed foods with added sugar and fat are engineered to minimize satiety per calorie.
+How does age affect calorie needs?
Calorie needs decline with age for two reasons: reduced muscle mass (sarcopenia) and decreased physical activity. After age 30, adults lose approximately 3–8% of muscle mass per decade without resistance training, and muscle burns significantly more calories at rest than fat. TDEE can decline 100–200 calories per decade in sedentary individuals. Resistance training is the most effective intervention — maintaining muscle mass preserves metabolic rate and significantly reduces age-related weight gain. Recalculate your TDEE every few years as your body composition and activity level change.
+What is the most accurate calorie formula?
Multiple studies comparing calorie formulas against metabolic testing (indirect calorimetry) consistently show that Mifflin-St Jeor is the most accurate for the general population, with an average error of approximately 5%. Harris-Benedict (an older formula) overestimates by about 5% on average. The Katch-McArdle formula is more accurate for lean individuals because it uses fat-free mass, but requires body fat percentage measurement. For most people without body composition testing, Mifflin-St Jeor provides the best available estimate.