# TDEE calculator: daily calories from the Mifflin-St Jeor equation Your total daily energy expenditure (TDEE) is your resting metabolic rate times an activity factor. This calculator estimates the resting rate with the Mifflin-St Jeor equation, multiplies it by your activity level, and shows a moderate deficit and surplus. Treat the result as a starting point and adjust after two to three weeks of real weigh-ins. ## How it works ### Resting rate (Mifflin-St Jeor) Men: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5. Women: the same with −161 instead of +5. It is the equation most dietitians use when body fat is unknown. ### Activity factor Sedentary 1.2, light 1.375, moderate 1.55, very active 1.725, athlete 1.9. Most people overestimate their activity; when in doubt, pick one level lower. ### Targets A deficit of about 500 kcal a day is a common starting point for fat loss, and a surplus of about 250 to 300 kcal for lean gain. Your weight trend over weeks is the real test. ## Questions ### How accurate is a TDEE calculator? Equations are typically within about 10% of measured resting energy for most adults, and less accurate at the extremes of body size. Use the number to start, then adjust by your 7-day average weight over two to three weeks. ### Should I eat back the calories I burn exercising? The activity factor already includes your usual training. Adding watch estimates on top usually double-counts, so keep the TDEE target and adjust from your weight trend. ### What deficit is safe? Around 500 kcal a day, or losing about 0.5% to 1% of body weight a week, is a common target. Very low intakes are not advised without medical supervision. ### Why does my weight not match the math? Water, salt, carbohydrate and digestion move daily weight by a kilogram or more. Compare 7-day averages, not single days. ## Sources - [Mifflin MD et al. A new predictive equation for resting energy expenditure. Am J Clin Nutr 1990](https://pubmed.ncbi.nlm.nih.gov/2305711/) Accurate as of November 12, 2026. --- Canonical: https://revns.com/tools/tdee-calculator Index of everything: https://revns.com/llms.txt revns gives training guidance, not medical advice.