Calculate your Total Daily Energy Expenditure
Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day, accounting for everything from breathing and digestion to walking and exercise. Knowing your TDEE is the foundation of any nutrition plan -- whether you want to lose weight, gain muscle, or maintain your current body composition. Without this number, calorie targets are essentially guesswork. TDEE is built on your Basal Metabolic Rate (BMR), which is the number of calories your body needs at complete rest to maintain basic life functions such as breathing, circulation, and cell production. BMR accounts for roughly 60-70% of total daily calorie expenditure in most people. The remaining calories are burned through physical activity, the thermic effect of food (energy used to digest meals), and non-exercise activity thermogenesis (NEAT) -- fidgeting, walking, and other incidental movement. This calculator uses the Mifflin-St Jeor equation, which is considered the most accurate BMR estimation formula for the general population according to research reviewed by the British Dietetic Association. Your BMR is then multiplied by an activity factor to estimate your TDEE.
To calculate your TDEE: 1. Enter your weight in kilograms. If you know your weight in stones or pounds, convert first: 1 stone = 6.35 kg, 1 pound = 0.45 kg. 2. Enter your height in centimetres. If you know your height in feet and inches, convert: 5 foot 10 = 178 cm, for example. 3. Enter your age in years. BMR decreases with age, so this value affects the result significantly. 4. Select your biological sex. Males and females have different BMR formulas due to differences in average body composition. 5. Choose your activity level. Be honest -- most people overestimate their activity. "Sedentary" means a desk job with little or no intentional exercise. "Lightly Active" means light exercise 1-3 days per week. "Moderately Active" means moderate exercise 3-5 days per week. "Active" means hard exercise 6-7 days per week. "Very Active" means intense daily exercise or a physically demanding job plus training. 6. View your results. The calculator shows both your BMR (calories at rest) and your TDEE (total daily calories including activity). Use the TDEE figure as your starting point for calorie planning.
The calculator uses the Mifflin-St Jeor equation to estimate BMR: For males: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5 For females: BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161 This equation was developed in 1990 and has been validated in numerous studies as more accurate than the older Harris-Benedict equation for modern populations. It accounts for the fact that larger, taller, and younger individuals burn more calories at rest, and that males generally have higher metabolic rates due to greater lean body mass. The BMR is then multiplied by an activity factor to produce the TDEE: Sedentary: BMR x 1.2 (little or no exercise) Lightly Active: BMR x 1.375 (light exercise 1-3 days/week) Moderately Active: BMR x 1.55 (moderate exercise 3-5 days/week) Active: BMR x 1.725 (hard exercise 6-7 days/week) Very Active: BMR x 1.9 (intense daily exercise or physical job) For example, a 30-year-old male weighing 80 kg at 180 cm tall has a BMR of approximately 1,780 kcal. At a "Moderately Active" level, his TDEE would be about 2,759 kcal per day.
TDEE is an estimate, not an exact figure. Individual metabolic rates vary due to genetics, body composition (muscle burns more than fat), hormonal factors, and adaptive thermogenesis. Use your calculated TDEE as a starting point and adjust based on real-world results over 2-4 weeks. The NHS Eatwell Guide suggests approximately 2,500 kcal per day for men and 2,000 kcal per day for women as general guidelines, but individual needs differ significantly.