BMR & Calorie Calculator
Find out how many calories your body burns at rest (BMR) and how many you need daily based on your activity level (TDEE). Get personalised calorie targets to lose, maintain, or gain weight.
Your Details
Basal Metabolic Rate (BMR)
1,643
kcal / day at rest
TDEE — Daily Calorie Needs
2,259 kcal
Lightly active · ×1.375
1,759
Lose weight (−500 kcal)
2,259
Maintain weight
2,759
Gain weight (+500 kcal)
How It Works
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest to maintain basic physiological functions — breathing, circulation, cell production, and temperature regulation. It accounts for roughly 60–70% of your total daily energy expenditure. The Mifflin-St Jeor equation (1990) is widely considered the most accurate BMR formula for non-athletic adults — it outperformed Harris-Benedict and other formulas in clinical validation studies. TDEE (Total Daily Energy Expenditure) = BMR × an activity multiplier that accounts for your physical activity level, from sedentary (desk job, no exercise) to very active (athletes or physically demanding jobs). To lose weight at ~0.5 kg/week, consume 500 kcal/day below your TDEE. To gain muscle at ~0.25 kg/week, consume 250–500 kcal above TDEE with adequate protein.
Formula
Mifflin-St Jeor: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5 (men) or − 161 (women). TDEE = BMR × activity multiplier.
Frequently Asked Questions
What is BMR and why does it matter?
BMR (Basal Metabolic Rate) is the number of calories your body needs just to stay alive — breathing, heartbeat, organ function, maintaining body temperature. It is the floor of your caloric needs. Knowing your BMR helps you understand how many calories you burn without any activity, which is essential for setting an accurate daily calorie target for weight management.
What is the difference between BMR and TDEE?
BMR is your calorie burn at absolute rest. TDEE (Total Daily Energy Expenditure) is BMR multiplied by an activity factor that accounts for exercise, daily movement, and non-exercise activity thermogenesis (NEAT). For most adults, TDEE is 1.2x–1.9x their BMR. TDEE is your actual daily calorie maintenance level — the number of calories needed to maintain current weight.
Which BMR formula is most accurate?
The Mifflin-St Jeor equation (1990) is most commonly recommended by registered dietitians and validated in multiple studies. It outperformed the Harris-Benedict equation (1919) and the Katch-McArdle formula (which requires body fat percentage). For athletes with known lean mass, the Katch-McArdle formula may be more accurate. Our calculator uses Mifflin-St Jeor.
How many calories should I eat to lose weight?
A deficit of 500 kcal/day below your TDEE theoretically produces about 0.5 kg of fat loss per week (3,500 kcal ≈ 0.45 kg of fat). In practice, metabolic adaptation reduces actual loss slightly. Most guidelines recommend not going below 1,200 kcal/day for women or 1,500 kcal/day for men, as very low intakes cause muscle loss and metabolic slowdown. A 300–500 kcal deficit is sustainable and effective.
Does BMR change over time?
Yes. BMR naturally declines with age (roughly 1–2% per decade after 30) as muscle mass decreases — muscle is metabolically more active than fat. Severe caloric restriction also reduces BMR (metabolic adaptation). Resistance training can maintain or increase BMR by preserving lean mass. Hormonal changes (thyroid, menopause) also affect BMR significantly.
What activity level should I select?
Sedentary (×1.2): desk job, no intentional 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. Super active (×1.9): physical job + training, or twice-daily workouts. Most people overestimate their activity level — when in doubt, go one level lower.