BMR & TDEE Calculator
Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation. Use it to set accurate calorie targets for fat loss, maintenance, or muscle gain.
About this calculator
Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest to sustain vital functions like breathing, circulation, and cell repair. This calculator uses the Mifflin-St Jeor equation, considered the most accurate for most adults: BMR (male) = 88.362 + (13.397 × weight kg) + (4.799 × height cm) − (5.677 × age). BMR (female) = 447.593 + (9.247 × weight kg) + (3.098 × height cm) − (4.330 × age). Total Daily Energy Expenditure (TDEE) is then found by multiplying BMR by an activity factor ranging from 1.2 (sedentary) to 1.9 (very active). TDEE represents the total calories you need to maintain your current weight given your lifestyle. Eating below TDEE creates a deficit for fat loss; eating above creates a surplus for muscle gain.
How to use
A 30-year-old male, 80 kg, 180 cm tall, with a moderate activity level (factor 1.55). BMR = 88.362 + (13.397 × 80) + (4.799 × 180) − (5.677 × 30) = 88.362 + 1,071.76 + 863.82 − 170.31 = 1,853.6 kcal/day. TDEE = 1,853.6 × 1.55 ≈ 2,873 kcal/day. To lose ~0.5 kg per week (a 500 kcal daily deficit), target approximately 2,373 kcal/day. To gain muscle, aim for a 200–300 kcal surplus at around 3,073–3,173 kcal/day.
Frequently asked questions
What is the difference between BMR and TDEE and which one should I use for dieting?
BMR is the calories your body needs if you did absolutely nothing — no movement at all — for 24 hours. TDEE adds your real-world activity on top of that baseline, making it the number that actually reflects your daily calorie needs. For any dietary goal — fat loss, maintenance, or muscle gain — you should use TDEE as your starting point, not BMR. Eating at BMR would leave most people severely underfed once normal daily movement is accounted for, which can slow metabolism and cause muscle loss over time.
How accurate is the Mifflin-St Jeor equation for calculating BMR?
The Mifflin-St Jeor equation is considered the most accurate general-population BMR formula, with studies showing it predicts measured resting metabolic rate within about 10% for roughly 80% of people. It outperforms the older Harris-Benedict equation, especially for overweight and obese individuals. However, it does not account for body composition — a very muscular person will have a higher true BMR than the equation predicts, because muscle tissue burns more calories at rest than fat. For the most accurate result, pair the equation's output with 2–4 weeks of tracked food intake and weight data.
Why does my TDEE change when I increase my activity level?
The activity multiplier applied to BMR is a practical estimate of the energy cost of your daily movement, from structured exercise to incidental steps throughout the day. Moving from sedentary (1.2) to lightly active (1.375) represents hundreds of additional calories burned daily — enough to meaningfully affect body composition over months. As you build fitness and exercise more, your TDEE rises, meaning you can eat more while still losing fat or maintaining weight. Recalculating your TDEE every 4–6 weeks as your weight and activity change keeps your calorie targets accurate.