Total Daily Energy Expenditure (TDEE) is arguably the most important metric you need to understand when embarking on any weight loss, muscle gain, or intermittent fasting journey. It represents the total number of calories your body burns in a 24-hour period, taking into account both your resting metabolic rate and your physical activity level. Use our scientifically-backed calculator below to find out your exact TDEE.
Calculate Your TDEE
Enter your physiological details below. Our algorithm uses the highly accurate Mifflin-St Jeor equation, which has been validated in multiple clinical trials as the most reliable formula for modern populations.
Understanding the Science: What Makes Up Your TDEE?
Your TDEE is the sum of three primary components of energy expenditure:
- Basal Metabolic Rate (BMR) — approx. 60-70%: Energy your body uses to maintain essential functions at rest — breathing, blood circulation, cellular repair, and brain function.
- Thermic Effect of Activity (TEA) — approx. 15-30%: All calories burned through movement, including formal exercise and Non-Exercise Activity Thermogenesis (NEAT): walking, fidgeting, and everyday chores.
- Thermic Effect of Food (TEF) — approx. 10%: Calories burned by digesting and metabolizing food. Protein has a significantly higher TEF than fats or carbohydrates.
The Mifflin-St Jeor Equation Explained
The calculator uses the Mifflin-St Jeor equation, published in 1990 in the American Journal of Clinical Nutrition. It replaced the older Harris-Benedict formula, which was found to overestimate caloric needs by approximately 5% in modern, more sedentary populations.
For men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
A systematic review by the Academy of Nutrition and Dietetics (PubMed) confirmed the Mifflin-St Jeor formula is the most accurate predictive equation for resting metabolic rate in healthy adults.
Activity Multipliers: From Sedentary to Extra Active
- Sedentary (×1.2): Desk job, little to no exercise.
- Lightly Active (×1.375): Light exercise 1–3 days/week.
- Moderately Active (×1.55): Moderate exercise 3–5 days/week.
- Very Active (×1.725): Hard exercise 6–7 days/week.
- Extra Active (×1.9): Physical job or twice-daily training.
Our calculator uses the sedentary multiplier (×1.2) as a conservative, safe baseline — most people overestimate their activity level.
How to Apply Your TDEE to Intermittent Fasting
Fasting dictates when you eat, while your TDEE dictates how much you should eat to reach your goals:
- Fat Loss: Eat 300-500 calories below your TDEE. This creates a sustainable caloric deficit, forcing your body to oxidize stored fat for fuel.
- Maintenance: Eat exactly your TDEE calories during your eating window.
- Lean Muscle Gain: Eat 200-300 calories above your TDEE to fuel muscle protein synthesis, combined with progressive resistance training.
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) recommends reducing intake by 500–750 calories per day for safe, sustainable weight loss of 0.5–1 kg per week.
Metabolic Adaptation: Why You Need to Recalculate
As you lose weight and your body adapts to a caloric deficit, your TDEE decreases — this is called metabolic adaptation. It is the most common reason for weight loss plateaus. Experts recommend recalculating your TDEE every 4-8 weeks and considering periodic refeeding days to prevent metabolic slowdown.
Take the Guesswork Out of Fasting
The FastingTracker app calculates your TDEE, tracks your fasting windows, logs your meals, and keeps you consistently in a fat-burning state.
Frequently Asked Questions
Does TDEE change every day?
Yes. While your BMR is relatively stable, your Thermic Effect of Activity varies daily based on your movement. The calculator gives a reliable average baseline.
Should I eat my TDEE to lose weight?
No. Eating exactly at your TDEE maintains your current weight. For fat loss, you must eat below your TDEE to create an energy deficit.
Is TDEE the same as calories burned?
Yes — your TDEE equals the total calories your body burns per day. Eating below it causes weight loss; eating above it causes weight gain.
Medical Sources & References
- Mifflin MD, St Jeor ST et al. (1990). A new predictive equation for resting energy expenditure. American Journal of Clinical Nutrition.
- Frankenfield D et al. (2005). Comparison of predictive equations for resting metabolic rate. Journal of the American Dietetic Association.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Weight Management Resources.