Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period. It is the "Master Variable" in any fitness transformation. Whether your goal is to add lean mass or strip away body fat, your TDEE is the starting line. Unlike your BMR (Basal Metabolic Rate), which only accounts for life-sustaining functions like breathing and heart rate, TDEE accounts for every movement you make, from blinking to heavy squats. Our calculator uses the Mifflin-St Jeor equation, widely considered the most accurate formula for modern, non-clinical populations.
One of the primary reasons "Hardgainers" fail to gain weight is a misunderstanding of NEAT. NEAT includes all the energy expended for everything we do that is not sleeping, eating, or sports-like exercise. It ranges from walking to the office to fidgeting at a desk. For some individuals, NEAT can account for a difference of up to 2,000 calories per day between two people of the same weight. If you find that the "Moderate Activity" setting isn't resulting in weight gain, it is likely that your NEAT is higher than average, requiring a manual adjustment to your caloric floor.
TDEE also includes the energy required to digest, absorb, and process the nutrients in your meals. This is known as the Thermic Effect of Food (TEF). Interestingly, different macronutrients require different amounts of energy to process. Protein has the highest TEF, requiring roughly 20-30% of its own calories just to be digested. This is a key reason why high-protein diets, as calculated in our Protein Optimizer, are so effective for body recomposition—they essentially "boost" your TDEE simply through the act of eating.
Your TDEE is not a static number. As you gain muscle through a successful bulk, your BMR increases because muscle is more metabolically "expensive" than fat. Conversely, if you stay in a caloric deficit for too long, your body may decrease its NEAT to conserve energy—a process known as Adaptive Thermogenesis. This is why we recommend re-calculating your TDEE every 3-5kg of weight change. Staying updated with your current TDEE ensures that your "Maintenance" numbers never become a "Deficit" by mistake.