Calculate your daily calorie needs (TDEE) based on age, weight, height, and activity level using the Mifflin-St Jeor formula.
Your daily calorie needs depend on your Basal Metabolic Rate (BMR) — the calories your body needs at complete rest — multiplied by an activity factor to get your Total Daily Energy Expenditure (TDEE). We use the Mifflin-St Jeor equation, the most accurate formula for most people:
Multiply BMR by your activity factor: 1.2 (sedentary), 1.375 (light exercise 1–3 days/week), 1.55 (moderate 3–5 days), 1.725 (heavy 6–7 days), 1.9 (very heavy / physical job + training) to get TDEE.
For weight loss: Eat 500 calories below TDEE to lose approximately 1 lb (0.45 kg) per week. For weight gain: eat 300–500 above TDEE. The minimum safe calorie intake is generally 1,200/day for women and 1,500/day for men.
Most calculators use the Mifflin-St Jeor equation to estimate basal metabolic rate (BMR): for men, 10×weight(kg) + 6.25×height(cm) − 5×age + 5; for women the same minus 161. BMR is then multiplied by an activity factor from 1.2 (sedentary) to 1.9 (very active) to give total daily energy expenditure (TDEE).
A 30-year-old woman, 165 cm and 65 kg, has a BMR of about 1,395 kcal. Moderately active (factor 1.55), her TDEE is roughly 2,160 kcal per day. A gentle 0.25–0.5 kg/week loss would target roughly 250–500 kcal below that.
Are these numbers exact? No — equations carry ±10% error and individual metabolism varies. Track real-world weight change over 2–3 weeks and adjust.
Is 1,200 kcal a safe floor? Very low targets risk nutrient deficiencies; consult a professional before aggressive deficits.