Calorie Calculator
Find out how many calories you need per day to lose weight, maintain weight, or gain weight — based on your age, height, weight, sex, and activity level.
How Are Daily Calorie Needs Calculated?
This calculator uses the Mifflin-St Jeor equation, published in 1990 and currently considered the most accurate predictor of resting metabolic rate for most adults. It calculates your Basal Metabolic Rate (BMR) — the calories burned at complete rest — then multiplies by an activity factor to estimate your Total Daily Energy Expenditure (TDEE).
The Mifflin-St Jeor Formula
Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
TDEE = BMR × Activity Factor
Activity multipliers explained
| Activity Level | Multiplier | Example |
|---|---|---|
| Sedentary | × 1.2 | Desk job, no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extra active | × 1.9 | Physical job + hard exercise daily |
Frequently Asked Questions
How many calories should I eat per day?
The average adult needs roughly 2,000–2,500 calories per day, but this varies significantly based on age, sex, weight, height, and activity level. This calculator uses the Mifflin-St Jeor equation — currently considered the most accurate — to estimate your specific daily calorie needs.
What is a BMR and how is it calculated?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest just to maintain basic functions — breathing, circulation, and cell production. The Mifflin-St Jeor formula: Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5. Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161.
What is a safe calorie deficit for weight loss?
A deficit of 500 calories per day produces approximately 0.5 kg (1 lb) of fat loss per week. A 750 calorie deficit produces about 0.75 kg per week. Going below 1,200 calories/day (women) or 1,500 calories/day (men) is generally not recommended without medical supervision as it can cause muscle loss and nutritional deficiencies.
What is TDEE?
TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor. It represents the total calories you burn each day including all physical activity. Your TDEE is the key number for weight management — eating below it causes weight loss, eating above it causes weight gain.
Does eating too few calories slow metabolism?
Yes — this is called adaptive thermogenesis. When calorie intake drops significantly, the body reduces its metabolic rate to conserve energy. This is why very low calorie diets often lead to plateaus. Moderate deficits (500 calories or less) with adequate protein intake minimise metabolic adaptation.
How accurate are calorie calculators?
Calorie calculators estimate needs based on population averages and are typically accurate to within 10–15% for most people. Individual metabolism varies due to genetics, gut microbiome, and hormones. Use the result as a starting point and adjust based on real-world results over 2–3 weeks.