Daily Calorie Needs Calculator
Find out how many calories your body needs each day to maintain, lose, or gain weight. Uses the Mifflin-St Jeor equation adjusted for your activity level.
About this calculator
This calculator uses the Mifflin-St Jeor equation, one of the most accurate formulas for estimating Basal Metabolic Rate (BMR) — the calories your body burns at complete rest. For men, the formula is: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age in years). The result is then multiplied by an activity factor (e.g. 1.2 for sedentary, 1.55 for moderately active, 1.725 for very active) to give your Total Daily Energy Expenditure (TDEE). TDEE represents the total calories you need to maintain your current weight. To lose weight, consume fewer calories than your TDEE; to gain, consume more. This method is more accurate than the older Harris-Benedict equation because it was validated on a modern population.
How to use
Suppose a 30-year-old man weighs 80 kg, is 175 cm tall, and exercises 3–5 days per week (activity factor = 1.55). Step 1 — Calculate BMR: 88.362 + (13.397 × 80) + (4.799 × 175) − (5.677 × 30) = 88.362 + 1071.76 + 839.825 − 170.31 = 1829.64 kcal/day. Step 2 — Multiply by activity factor: 1829.64 × 1.55 = 2835.9 kcal/day. This man needs approximately 2,836 calories per day to maintain his weight. To lose 0.5 kg per week, he would subtract ~550 kcal, targeting roughly 2,286 kcal/day.
Frequently asked questions
How accurate is the Mifflin-St Jeor equation for calculating daily calorie needs?
The Mifflin-St Jeor equation is considered the most accurate predictive formula for most adults, with studies showing it estimates resting metabolic rate within 10% for roughly 82% of people. However, it is still an estimate — individual factors like muscle mass, hormonal health, and genetics can cause real-world needs to differ. For best results, track your weight for 2–3 weeks at the calculated intake and adjust from there. People with very high or very low body fat percentages may find the formula less precise.
What activity level multiplier should I use for the daily calorie calculator?
Activity multipliers typically range from 1.2 (sedentary — desk job, little exercise) to 1.9 (extremely active — hard physical labor or twice-daily training). A moderately active person who exercises 3–5 days per week uses 1.55. It is common to underestimate activity level, which can lead to overeating, so be honest about your typical week rather than your best week. If unsure, start with a lower multiplier and monitor your weight over a few weeks.
How many calories should I eat per day to lose weight safely?
A calorie deficit of 500–750 kcal per day below your TDEE is generally recommended to lose approximately 0.5–0.75 kg per week, which is considered a safe and sustainable rate. Dropping below 1,200 kcal/day for women or 1,500 kcal/day for men is not recommended without medical supervision, as it risks nutrient deficiencies and muscle loss. Combining a moderate calorie deficit with adequate protein intake and resistance training preserves lean muscle during weight loss. Always consult a healthcare professional before making major dietary changes.