1,699
kcal/day
2,633
kcal/day
2,633
kcal/day
0
kcal/day
135
g/day
88
g/day
326
g/day
540
kcal/day
790
kcal/day
1,303
kcal/day
1,699
kcal/day
2,633
kcal/day
2,633
kcal/day
0
kcal/day
135
g/day
88
g/day
326
g/day
540
kcal/day
790
kcal/day
1,303
kcal/day
The Calorie Calculator determines your personalized daily calorie needs based on your age, gender, weight, height, and activity level. Whether your goal is weight loss, weight maintenance, or muscle gain, understanding your daily calorie target is the foundational first step in any effective nutrition plan. This calculator uses the Mifflin-St Jeor equation, the most accurate formula for estimating resting metabolic rate available for the general population.
Calories are the basic unit of food energy. Every physiological process — from breathing and pumping blood to walking and thinking — requires energy derived from the foods you eat. The Basal Metabolic Rate (BMR) represents the number of calories your body requires simply to maintain vital functions at complete rest. Your BMR accounts for approximately 60–75% of your total daily calorie expenditure.
Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor that accounts for your exercise and movement level. Activity multipliers range from 1.2 (sedentary, desk job) to 1.9 (extra active, physical labor plus daily exercise). The difference between a sedentary and very active lifestyle can represent 500–1,000 calories per day in energy expenditure — a difference that dramatically affects the calorie target needed to achieve any given goal.
The Mifflin-St Jeor equation, developed in 1990, calculates BMR as: For men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. For women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161. A 2005 meta-analysis published in the Journal of the American Dietetic Association by Frankenfield et al. found the Mifflin-St Jeor equation to be the most accurate predictor of resting metabolic rate in non-obese individuals, correctly predicting measured BMR within 10% in 82% of subjects.
To achieve weight loss, a calorie deficit is required. A deficit of approximately 550 kcal/day produces ~0.5 kg of weight loss per week (based on 7,700 kcal = 1 kg of body fat). A deficit of 1,100 kcal/day theoretically produces ~1 kg/week, though this should only be attempted under medical supervision. This calculator enforces a minimum of 1,200 kcal/day for safety — below this threshold, essential nutrient intake becomes inadequate for most adults.
For weight gain, a calorie surplus of 550 kcal/day supports approximately 0.5 kg/week of weight gain. Combined with resistance training, this surplus supports muscle hypertrophy with minimal fat gain — a strategy used by bodybuilders and athletes in the "bulking" phase of training.
Alongside your calorie target, this calculator recommends macronutrient targets: approximately 25% of calories from protein (supporting muscle maintenance and satiety), 45% from carbohydrates (primary fuel for brain and muscles), and 30% from fats (supporting hormone production, fat-soluble vitamin absorption, and cell membrane integrity). These ratios align with the Acceptable Macronutrient Distribution Ranges (AMDRs) established by the Institute of Medicine.
BMR is calculated using the Mifflin-St Jeor equation (1990): Male: 10W + 6.25H − 5A + 5 | Female: 10W + 6.25H − 5A − 161 (W = weight kg, H = height cm, A = age years). TDEE = BMR × Activity Factor (sedentary: 1.2, light: 1.375, moderate: 1.55, active: 1.725, extra active: 1.9). Goal calories = TDEE + adjustment (maintain: 0, lose 0.5 kg/week: −550, lose 1 kg/week: −1100, gain 0.5 kg/week: +550, gain 1 kg/week: +1100). Macros: Protein = Goal Cal × 0.25 ÷ 4; Carbs = Goal Cal × 0.45 ÷ 4; Fat = Goal Cal × 0.30 ÷ 9.
Your BMR is the absolute minimum calories your body needs at rest. Never eat below your BMR for extended periods. Your TDEE is your maintenance calorie level. For weight loss, eat below your TDEE; for gain, above it. A moderate deficit of 300–500 kcal/day produces safe, sustainable weight loss of 0.3–0.5 kg/week. Aggressive deficits (>750 kcal) increase muscle loss risk. Protein recommendations should be treated as a minimum — many athletes consume 1.6–2.2 g/kg body weight for optimal muscle preservation.
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Results
BMR of 1,884 kcal/day scales to TDEE of 2,920 kcal with moderate activity (×1.55). Macros: 183g protein, 329g carbs, 97g fat supports maintenance with balanced nutrient intake.
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Results
TDEE of 1,935 kcal minus 550 kcal deficit = 1,385 kcal goal. At this intake, expected loss is ~0.5 kg/week. Protein at 87g/day helps preserve muscle during caloric restriction.
The Mifflin-St Jeor equation, developed by Mifflin et al. in 1990, calculates BMR as: Males: (10 × kg) + (6.25 × cm) − (5 × age) + 5; Females: (10 × kg) + (6.25 × cm) − (5 × age) − 161. It is considered the most accurate BMR formula for the general population, validated in a 2005 meta-analysis by Frankenfield et al.
BMR (Basal Metabolic Rate) is calories burned at complete rest. TDEE (Total Daily Energy Expenditure) is your total daily calorie burn including all physical activity. TDEE = BMR × Activity Factor.
For safe, sustainable weight loss, eat 300–550 kcal below your TDEE. This creates a 0.3–0.5 kg/week deficit. Avoid going below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision.
The Mifflin-St Jeor equation predicts measured BMR within 10% for approximately 82% of non-obese adults (Frankenfield et al., 2005). Activity multipliers add further variability. Consider results as estimates requiring adjustment based on real-world results over 2–4 weeks.
Yes. BMR decreases approximately 1–2% per decade after age 20, primarily due to decreasing muscle mass (sarcopenia). A 60-year-old has a meaningfully lower BMR than a 30-year-old of the same height and weight, requiring fewer calories for weight maintenance.
Average calorie needs for adult women range from approximately 1,600 kcal/day (sedentary, older) to 2,400 kcal/day (active, younger). Individual needs vary significantly based on height, weight, age, and activity level — use this calculator for personalized estimates.
One kilogram of body fat contains approximately 7,700 kilocalories of stored energy. This means a daily deficit of 550 kcal = ~3,850 kcal/week ≈ 0.5 kg/week weight loss. This relationship, while approximate, is the basis of calorie-deficit weight loss planning.
If you already selected an accurate activity level, exercise is already factored into your TDEE — you should not eat additional calories for exercise. If you selected a lower activity level for baseline tracking, eating back a portion (50–75%) of exercise calories is a reasonable adjustment.
The generally accepted minimum is 1,200 kcal/day for women and 1,500 kcal/day for men to meet basic micronutrient requirements. Below these levels, nutritional deficiencies become likely without careful supplementation and medical oversight.
Total calorie balance drives weight change, but macronutrient ratios affect body composition and hunger. Higher protein intake (25–30% of calories) preserves muscle during deficit and increases satiety. Complex carbohydrates provide sustained energy. Adequate fat supports hormones and fat-soluble vitamins.
Roboculator Team
The Roboculator Team explains calculations, planning tools, and practical formulas in clear language for real-life situations.
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