BMR & Daily Calorie Calculator
Calculate your Basal Metabolic Rate and total daily calorie needs using the revised Harris-Benedict equation. Useful for weight loss, maintenance, or muscle gain planning based on your activity level.
Last updated: September 2026
Formula below · 2 sources (dietaryguidelines.gov, Wikipedia) · Updated Sep 2026
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About this calculator
This calculator uses the revised Harris-Benedict equation (Roza & Shizgal, 1984) to estimate Basal Metabolic Rate (BMR) — the calories your body burns at complete rest. For men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) − (5.677 × age). For women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) − (4.330 × age). Total Daily Energy Expenditure (TDEE) is then calculated by multiplying BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (extremely active). This accounts for all physical activity on top of baseline metabolism. The newer Mifflin-St Jeor equation (1990) is often preferred by dietitians and usually gives a BMR about 5% lower than Harris-Benedict for the same person; both are typically accurate within ±10% for most adults, so treat the result as a starting point and adjust from your real weight trend.
How to use
Example: a 30-year-old male weighing 80 kg and 180 cm tall with a moderately active lifestyle (activity factor 1.55). BMR = 88.362 + (13.397 × 80) + (4.799 × 180) − (5.677 × 30) = 88.362 + 1071.76 + 863.82 − 170.31 = 1853.63 kcal/day. TDEE = 1853.63 × 1.55 ≈ 2873 kcal/day. To lose weight, subtract ~500 kcal for a target of about 2,373 kcal/day; to gain muscle, add ~300 kcal for a target of about 3,173 kcal/day.
Frequently asked questions
What is the difference between BMR and TDEE and which one should I use for my diet?
BMR is the number of calories your body needs to sustain basic life functions — breathing, circulation, and cell repair — while completely at rest. TDEE adds the energy cost of all your daily movement and exercise on top of BMR. For practical diet planning, always use your TDEE, not your BMR, because no one is truly at rest all day. Setting calorie intake based on BMR alone would create an unintentional and potentially harmful deficit.
How accurate is the Mifflin-St Jeor equation for calculating calorie needs?
The Mifflin-St Jeor equation is considered the most accurate predictive equation for most adults, validated in studies to be within approximately 10% of measured resting metabolic rate for 82% of individuals. However, it is an estimate and cannot account for individual metabolic variation, muscle mass, hormonal status, or medical conditions like hypothyroidism. Very muscular individuals may find it underestimates their needs, while those with high body fat may find it overestimates. Tracking actual weight change over 2–4 weeks and adjusting calories accordingly remains the most reliable calibration method.
How much of a calorie deficit or surplus should I create to lose fat or gain muscle without negative side effects?
A deficit of 300–500 kcal per day is generally recommended for sustainable fat loss, resulting in approximately 0.3–0.5 kg of weight loss per week. Larger deficits can accelerate weight loss but increase muscle loss risk, fatigue, and nutrient deficiencies. For muscle gain, a modest surplus of 200–350 kcal per day is considered optimal for lean bulking, minimizing excess fat accumulation. Aggressive bulking surpluses above 500 kcal tend to add significant body fat alongside muscle.