Calorie & TDEE Calculator

TDEE (Total Daily Energy Expenditure) is the total calories your body burns in a day, including basal metabolism, digestion, and physical activity. It is calculated by multiplying BMR by an activity factor: sedentary (×1.2), lightly active (×1.375), moderately active (×1.55), very active (×1.725), or extra active (×1.9). TDEE is the foundation of any calorie-based nutrition plan. Eating at TDEE maintains weight; below TDEE creates a deficit for fat loss; above TDEE creates a surplus for muscle gain.

One pound of fat contains approximately 3,500 calories. To lose 1 lb/week, you need a 500 calorie daily deficit (500 × 7 = 3,500). To lose 0.5 lbs/week, a 250 calorie deficit. To lose 2 lbs/week, a 1,000 calorie deficit. Most experts recommend losing no more than 1-1.5 lbs/week for most people, as faster loss increases the risk of losing lean muscle. Never eat below 1,200 cal/day (women) or 1,500 cal/day (men) for extended periods without medical supervision.

The Mifflin-St Jeor equation (1990) is widely considered the most accurate for the general population. A landmark 2005 study in the Journal of the American Dietetic Association found it predicted resting metabolic rate within 10% for 82% of participants, outperforming the older Harris-Benedict equation (which overestimates by about 5%). For highly muscular or athletic individuals with known body fat percentage, the Katch-McArdle formula (using lean body mass) may be more accurate. For obese individuals, Mifflin-St Jeor using actual body weight is generally more reliable than ideal weight-based adjustments.

The most common reasons: (1) Overestimating activity level — this is the most frequent error; a desk job with 3 gym sessions per week is lightly active, not moderately. (2) Inaccurate food tracking — studies consistently show people underestimate calorie intake by 20-40%, especially from cooking fats, sauces, and snacks. (3) Metabolic adaptation — after weeks of dieting, BMR decreases by 10-20% beyond what weight loss alone explains. (4) Water retention masking fat loss — weight can stay stable for weeks while fat is being lost due to water retention from stress, hormones, or sodium. Track for 4 weeks then adjust by 100-200 calories if progress stalls.

For a lean bulk: eat 200-300 calories above TDEE. This provides energy for muscle synthesis while minimizing fat gain. Combined with progressive resistance training and 1.6-2.2g protein per kg of body weight, this approach builds muscle at approximately 0.5-2 lbs per month for natural lifters. A more aggressive surplus of 500 cal/day builds faster but adds significantly more fat. Note: beginners ("newbie gains") and people returning after a break can often achieve body recomposition at maintenance calories or even a slight deficit, gaining muscle while losing fat simultaneously.

Yes — this is called metabolic adaptation or adaptive thermogenesis. When calories are chronically restricted, the body reduces BMR by 10-20% beyond what is explained by weight loss alone. The body also reduces NEAT (non-exercise activity thermogenesis — fidgeting, posture, general movement) which can reduce calorie burn by another 100-300 calories/day. Strategies to minimize adaptation: avoid deficits greater than 25% of TDEE, take diet breaks (return to maintenance for 1-2 weeks every 4-6 weeks), maintain protein intake (1.8-2.4g/kg during aggressive deficits), and prioritize resistance training to preserve lean muscle mass.

Significantly. Lean muscle mass (not total body weight) is the primary driver of metabolic rate. Muscle burns approximately 3 times more calories at rest than fat tissue (roughly 6 cal/lb/day for muscle vs 2 cal/lb for fat). Two people of identical age, height, and weight but different body compositions can have BMRs that differ by 200-400 calories per day. This is why highly muscular individuals have higher calorie needs than the formula predicts from weight alone. For lean/athletic individuals, the Katch-McArdle formula (BMR = 370 + 21.6 × lean body mass in kg) is more accurate than height/weight-based formulas.

Macros (macronutrients) are protein, carbohydrates, and fat. Each provides calories: protein = 4 cal/g, carbohydrates = 4 cal/g, fat = 9 cal/g. A common starting point for body recomposition: protein 30% of calories (roughly 1.6g per kg of body weight), carbohydrates 40%, fat 30%. For fat loss, increasing protein to 35-40% of calories helps preserve lean mass and increases satiety. For endurance athletes, carbohydrates may increase to 50-60%. For low-carb approaches, fat increases to 50-60%. There is no single "correct" macro ratio — total calorie intake relative to TDEE matters most, but macros influence body composition and hunger within the same calorie budget.

Formula-based TDEE calculators have approximately 10-15% individual variation from actual measured values. Sources of inaccuracy: individual metabolic variation not captured by height/weight/age, body composition differences (muscular vs. overfat at same weight), hormonal differences (thyroid function, insulin sensitivity), chronic medication use, and particularly the subjective nature of activity level selection. For most people, the formula provides a reasonable starting point. The key is to treat the number as an initial estimate, track actual weight change for 3-4 weeks, and adjust by 100-200 calories up or down based on real results rather than assuming the formula is perfectly accurate for your individual metabolism.

It depends on how you set your TDEE. If you used a higher activity multiplier that already accounts for your exercise (e.g., "very active" for daily hard training), your TDEE already includes those calories and you should not eat them back. If you used "sedentary" and then exercise, you may eat back 50-75% of estimated exercise calories (not 100%, as exercise calorie estimates are notoriously inaccurate and tend to overestimate by 50-100%). The simplest approach for most people: use a moderate activity multiplier that reflects your average weekly activity, eat at that TDEE consistently, and don't try to adjust day-by-day based on individual workout sessions.