TDEE Calculator - Calculate Your Total Daily Energy Expenditure Using Scientific Methods

Mifflin-St Jeor Equation (Recommended)

Considered the most accurate for the general population, this formula was developed in 1990 and accounts for modern lifestyle changes. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5. For women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161. This method has been validated across diverse populations and provides reliable estimates for most individuals.

Harris-Benedict Equation (Classic)

The original BMR formula from 1919, revised in 1984. While historically significant, it tends to overestimate calorie needs by 5-15% in modern sedentary populations. For men: BMR = 88.362 + (13.397 × weight in kg) + (4.799 × height in cm) - (5.677 × age). For women: BMR = 447.593 + (9.247 × weight in kg) + (3.098 × height in cm) - (4.330 × age). Still useful for comparison and research purposes.

Katch-McArdle Formula (Body Composition Based)

The most accurate method when body fat percentage is known, as it accounts for lean body mass directly. BMR = 370 + (21.6 × lean body mass in kg). This formula recognizes that muscle tissue is metabolically more active than fat tissue, making it ideal for athletes, bodybuilders, or individuals with known body composition. Requires accurate body fat measurement for optimal results.

Activity Level Multipliers

Sedentary (BMR × 1.2): desk job, no exercise. Lightly active (BMR × 1.375): light exercise 1-3 days/week. Moderately active (BMR × 1.55): moderate exercise 3-5 days/week. Very active (BMR × 1.725): hard exercise 6-7 days/week. Extremely active (BMR × 1.9): very hard exercise, physical job, or training twice daily. These multipliers account for all daily movement beyond resting metabolism.

Healthy Weight Loss Guidelines

Safe weight loss occurs at 0.5-2 pounds per week, requiring a calorie deficit of 250-1000 calories daily (1 pound = 3500 calories). Moderate deficits of 500-750 calories daily optimize fat loss while preserving muscle mass. Extreme calorie restriction below BMR can slow metabolism, cause muscle loss, and lead to nutritional deficiencies. Combine calorie reduction with resistance training and adequate protein intake.

Sustainable Weight Gain Strategies

Healthy weight gain targets 0.5-1 pound per week through a calorie surplus of 250-500 calories daily. Focus on nutrient-dense foods and combine surplus calories with resistance training to promote muscle growth over fat gain. Rapid weight gain often results in excessive fat accumulation. Progressive overload training and adequate protein (0.8-1g per pound body weight) optimize muscle protein synthesis.

Body Recomposition Approach

Simultaneous fat loss and muscle gain is possible, especially for beginners, those returning to training, or individuals with higher body fat. Eat at or slightly below TDEE while prioritizing protein intake (1-1.2g per pound body weight) and consistent resistance training. Progress is measured through body composition changes rather than scale weight. This approach requires patience but creates lasting physique improvements.

Metabolic Adaptation and Diet Breaks

Extended calorie restriction can reduce metabolic rate by 10-25% through adaptive thermogenesis. Planned diet breaks (1-2 weeks at maintenance calories) every 6-12 weeks can help restore metabolic rate and improve long-term adherence. Reverse dieting gradually increases calories back to maintenance levels, allowing metabolism to recover while minimizing fat regain.

Myth: "Eating More Frequently Boosts Metabolism"

Fact: Meal frequency has minimal impact on total daily energy expenditure. The thermic effect of food depends on total daily intake, not meal timing. Whether you eat 3 large meals or 6 small meals, the metabolic boost from digestion remains approximately the same. Choose meal frequency based on personal preference, hunger patterns, and lifestyle convenience rather than metabolic benefits.

Myth: "Muscle Burns 50+ Calories Per Pound Daily"

Fact: Each pound of muscle burns approximately 6-7 calories daily at rest, while fat burns 2-3 calories per pound. While muscle is more metabolically active than fat, the difference is smaller than commonly claimed. However, muscle mass significantly impacts overall calorie burn through increased capacity for physical activity and improved insulin sensitivity.

Myth: "Metabolism Slows Dramatically After 30"

Fact: While BMR does decline with age, the primary cause is muscle mass loss rather than age itself. Research shows metabolism remains relatively stable from ages 20-60 when controlling for body composition. Maintaining muscle mass through resistance training and staying active can largely prevent age-related metabolic decline.

Myth: "Starvation Mode Prevents Weight Loss"

Fact: While prolonged calorie restriction does reduce metabolic rate through adaptive thermogenesis, true "starvation mode" where weight loss stops completely doesn't occur in healthy individuals with adequate fat stores. Metabolic adaptation typically reduces BMR by 10-25%, not enough to completely halt weight loss with appropriate calorie deficits.

Myth: "Certain Foods Have Negative Calories"

Fact: No foods require more calories to digest than they provide. While some foods like celery have very low calorie content and high thermic effect, they still provide net calories. The thermic effect of food typically ranges from 8-15% of calories consumed, with protein having the highest effect at 20-30%.

How accurate are TDEE calculators?

TDEE calculators provide estimates within 10-20% accuracy for most people. Individual factors like genetics, metabolic efficiency, and NEAT can cause significant variation. Use calculated values as starting points and adjust based on real-world results over 2-4 weeks. Track weight changes, energy levels, and performance to fine-tune calorie intake for your specific needs.

Should I eat exactly my TDEE calories every day?

Your daily calorie target depends on your goals. Eat at TDEE to maintain weight, below TDEE to lose weight, and above TDEE to gain weight. Most people benefit from consistency within 100-200 calories of their target. Weekly averages matter more than daily precision, allowing flexibility for social events and appetite variations.

Why might my actual needs differ from calculated TDEE?

Individual variation in metabolism can be substantial due to genetics, medical conditions, training history, and lifestyle factors. NEAT alone can vary by 600+ calories between similar individuals. Some people are naturally more fidgety, have different muscle fiber types, or varying thyroid function. Always adjust calculations based on real-world results.

How do I know if my calorie intake is appropriate?

Monitor weight trends over 2-4 weeks, energy levels throughout the day, workout performance, and overall wellbeing. Appropriate calorie intake should support your goals while maintaining stable energy, good sleep, and healthy hormone function. Rapid weight changes, extreme fatigue, or loss of menstrual function may indicate inappropriate calorie levels.

Does exercise increase my daily calorie needs?

Yes, but the relationship is complex. While exercise burns calories during activity, it may also affect NEAT, appetite, and recovery needs. Some people unconsciously reduce daily activity after intense workouts. Track overall activity levels and adjust calorie intake based on total weekly exercise volume rather than individual workout sessions.

How often should I recalculate my TDEE?

Recalculate when body weight changes by 10+ pounds, activity levels change significantly, or every 3-6 months during active weight management. BMR decreases as body weight decreases, requiring calorie adjustments to maintain progress. Regular recalculation ensures your targets remain appropriate for your current status.

What role does body fat percentage play in metabolism?

Muscle tissue is more metabolically active than fat tissue, so body composition significantly affects BMR. Two people of the same weight can have vastly different calorie needs based on muscle-to-fat ratio. If you know your body fat percentage, use the Katch-McArdle formula for more accurate results, especially if you're very lean or muscular.

Can medications or medical conditions affect my TDEE?

Yes, thyroid disorders, diabetes, PCOS, and certain medications can significantly impact metabolic rate. Some antidepressants, corticosteroids, and insulin can affect energy expenditure and appetite. If you have medical conditions or take medications, work with healthcare providers to adjust calorie targets and monitor metabolic health markers.