The Calorie Calculator computes your daily calorie needs based on body data, age, and physical activity level.
Uses the Mifflin-St Jeor equation recommended by the American Dietetic Association. Displays BMR (basal metabolic rate), TDEE (total daily energy expenditure), and macronutrient distribution (carbohydrates, protein, fat) according to your goal — lose, maintain, or gain weight.
Disclaimer: Results are estimates. For specific diet programs or health conditions, consult a nutritionist or doctor.
Calculator information
📋 How to use this calculator
- Enter your sex, age (years), height (cm or inches), and weight (kg or lbs).
- Select your activity level: Sedentary (desk job, no exercise), Light (exercise 1-3x/week), Moderate (3-5x/week), Heavy (6-7x/week), or Very Heavy (athlete, physical labor).
- Choose a goal: lose weight (500 kcal deficit), maintain, or gain weight (500 kcal surplus).
- Click calculate to see your BMR (resting calories), TDEE (daily total), and target calories.
- Review the macronutrient breakdown: protein, carbohydrates, and fat in grams per day.
- Record your daily calorie target and track it with a food-logging app such as MyFitnessPal or Cronometer.
🧮 Mifflin-St Jeor BMR and TDEE
BMR (male) = 10*W + 6.25*H - 5*A + 5; BMR (female) = 10*W + 6.25*H - 5*A - 161; TDEE = BMR * Activity Factor
- W = weight in kg, H = height in cm, A = age in years
- Activity Factor: Sedentary 1.2; Light 1.375; Moderate 1.55; Heavy 1.725; Very Heavy 1.9
- Calorie deficit = TDEE - 500 (lose ~0.5 kg/1 lb per week)
- Calorie surplus = TDEE + 500 (gain ~0.5 kg/1 lb per week)
- Macros: Protein 1.6-2.2 g/kg body weight, Fat 20-30% of calories, Carbs the remainder
Mifflin-St Jeor is more accurate (~10% error) than the older Harris-Benedict equation. Recommended by the Academy of Nutrition and Dietetics.
💡 Worked example: Woman, 30 years old, 165 cm, 60 kg, moderate activity, wants to lose weight
Given:- Sex = Female
- Age = 30 years, Height = 165 cm, Weight = 60 kg
- Moderate activity = factor 1.55
- Goal = lose weight (500 kcal deficit)
Steps:- BMR = (10 x 60) + (6.25 x 165) - (5 x 30) - 161
- BMR = 600 + 1,031.25 - 150 - 161 = 1,320 kcal/day
- TDEE = 1,320 x 1.55 = 2,046 kcal/day
- Weight-loss target = 2,046 - 500 = 1,546 kcal/day
- Protein: 1.8 x 60 = 108 g (432 kcal)
- Fat: 25% x 1,546 = 386.5 kcal / 9 = 43 g
- Carbs: 1,546 - 432 - 386.5 = 727.5 kcal / 4 = 182 g
Result: Target ~1,546 kcal/day with 108 g protein, 182 g carbs, 43 g fat. Expected weight loss of ~0.5 kg (1 lb) per week with consistency.
❓ Frequently asked questions
How accurate is the Mifflin-St Jeor equation?
The Mifflin-St Jeor equation was developed in the US and has a margin of error of ~10% for the general population. Individual factors (genetics, thyroid hormones, body composition) also influence accuracy. Use the calculator's output as a starting estimate, then monitor body weight and waist circumference for 2-4 weeks and adjust calories by 100-200 kcal if no change occurs.
Does a 500 kcal deficit always result in 1 lb/week loss?
The theory that 1 lb of fat = 3,500 kcal means a 500/day deficit = 3,500/week = 1 lb/week, but practice is more complex. The body adapts by lowering BMR after a few weeks of dieting (metabolic adaptation). Initial loss is mostly water and glycogen, not fat. Realistically: 0.7-1.5 lb/week for a 500 kcal deficit. Extreme deficits (>1,000 kcal) risk muscle loss and rebound.
How much protein do I need to build muscle?
For muscle hypertrophy, the International Society of Sports Nutrition recommends 1.6-2.2 g protein/kg body weight/day, divided across 3-5 meals. Beginner athletes or sedentary individuals need 1.2-1.6 g/kg. Quality protein sources: eggs, chicken breast, fish, lean meat, tofu, tempeh, dairy, legumes. Combining protein with resistance training 2-4x/week produces optimal results.
Should exercise be counted as additional activity?
TDEE activity factors already include regular exercise. Moderate activity (1.55) = exercise 3-5x/week at moderate intensity. If you track workouts separately (with a fitness watch), choose a lower factor (Sedentary 1.2) and add exercise calories manually. Caution: smartwatches often overestimate calorie burn by 20-50%. It's better to underestimate exercise calories or use TDEE as a fixed baseline.
Is a calorie deficit safe during pregnancy and breastfeeding?
No. Pregnant women need an additional 300-500 kcal/day in trimesters 2-3, and breastfeeding mothers need an extra 450-500 kcal/day per CDC and ACOG guidance. A calorie deficit during these periods risks impaired fetal growth or reduced milk supply. Consult your doctor or a registered dietitian before dieting. This calculator is not recommended for pregnant/breastfeeding women, children <18, adults >65, or those with eating disorders.
📚 Sources & references
Last updated: May 11, 2026