How your calorie needs are calculated
Step 1 — BMR. Your basal metabolic rate is estimated with the Mifflin-St Jeor equation:
Men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5
Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
Step 2 — TDEE. BMR is multiplied by an activity factor: 1.2 (sedentary), 1.375 (light), 1.55 (moderate), 1.725 (very active) or 1.9 (extra active).
Step 3 — Goal. About 7,700 kcal equals 1 kg of body weight (3,500 kcal per pound), so losing 0.5 kg a week needs a daily deficit of about 550 kcal.
Example: A 30-year-old man, 180 cm (5 ft 11 in) and 80 kg (176 lb), who exercises 3–5 days a week. BMR = 800 + 1,125 − 150 + 5 = 1,780 kcal. TDEE = 1,780 × 1.55 = 2,759 kcal to maintain weight. To lose about 0.5 kg (1 lb) a week, he would eat roughly 2,209 kcal a day.
Making the numbers work
- Pick your activity level honestly. Most people with desk jobs who exercise a few times a week fit “lightly” or “moderately active”.
- Prioritize protein when cutting calories to preserve muscle — see the macro calculator.
- Recalculate as your weight changes. A smaller body burns fewer calories, so your target drops over time.
- Use a trend, not a single weigh-in. Daily weight can swing 1–2 kg with water and food.
These are estimates for healthy adults. Pregnant or breastfeeding women, people with medical conditions and competitive athletes should consult a doctor or registered dietitian.
Frequently asked questions
How many calories do I need a day?
Most adults need roughly 1,600–2,400 calories (women) or 2,000–3,000 calories (men), depending on size, age and activity. This calculator estimates your personal total daily energy expenditure (TDEE) from your measurements.
How many calories should I cut to lose weight?
A deficit of about 500 calories a day leads to roughly 0.5 kg (1 lb) of weight loss per week for most people. Larger deficits work faster but are harder to sustain and can cost muscle.
Which formula does this calculator use?
It uses the Mifflin-St Jeor equation, which studies have found to be the most accurate of the common equations for estimating resting metabolism in healthy adults, then multiplies it by an activity factor.
Why am I not losing weight at the calculated calories?
Calculators give estimates with an error of about ±10%. Food logging is also often underestimated. Track your weight for 2–3 weeks; if it isn’t moving as expected, adjust your intake by 100–200 calories.
Is it safe to eat below 1,200 calories?
Very low intakes make it hard to meet nutrient needs. General guidance is not to go below about 1,200 calories a day for women or 1,500 for men without medical supervision. The calculator flags goals below these levels.