Calorie Calculator

This calculator uses a two-step process: first it estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, then multiplies by an activity factor to determine your Total Daily Energy Expenditure (TDEE).

Activity Multipliers

Example Calculation

30-year-old male, 175 cm, 75 kg, moderately active:

• • BMR = (10 × 75) + (6.25 × 175) − (5 × 30) + 5 = 1,694 cal/day
• • TDEE = 1,694 × 1.55 = 2,625 cal/day
• • Weight loss (−500): 2,125 cal/day → ~0.5 kg/week
• • Weight gain (+500): 3,125 cal/day → ~0.5 kg/week

Calorie Deficit Guidelines

• 250 cal deficit: ~0.25 kg/week — very sustainable, minimal hunger
• 500 cal deficit: ~0.5 kg/week — standard recommendation, sustainable
• 1000 cal deficit: ~1 kg/week — aggressive, may lose muscle without adequate protein
• Safety floor: Never below 1,500 (men) / 1,200 (women) without medical supervision

Calorie Counting vs Intuitive Eating

Calorie counting provides objective data and accountability, making it effective for short-term goals like contest prep or hitting a target weight. Intuitive eating focuses on hunger cues and food quality rather than numbers, which can be more sustainable long-term but harder to calibrate initially. Many people use calorie tracking for 2-3 months to build awareness of portion sizes, then transition to intuitive eating once they have a reliable mental model of what their daily intake looks like.

How Activity Level Affects Your Daily Calories

The biggest variable in daily calorie expenditure between individuals isn't gym time — it's NEAT (Non-Exercise Activity Thermogenesis). NEAT includes all movement outside formal exercise: walking, fidgeting, cooking, cleaning, and even how much you gesticulate while talking. Two people with identical BMRs who both "go to the gym 3x/week" can differ by 500-800 calories daily based on whether they have a desk job vs. a retail job, take stairs vs. elevators, or pace while on calls vs. sitting still. When selecting your activity level above, consider your entire day — not just your workout.

Limitations

While the Mifflin-St Jeor equation is the most validated formula for estimating caloric needs, it has inherent limitations:

• Estimates BMR within ±10% — individual metabolism varies based on genetics, hormones, gut microbiome
• Activity multipliers are broad categories — actual expenditure depends on duration, intensity, body weight
• Does not account for thermic effect of food (~10% of intake), non-exercise activity thermogenesis (NEAT), or adaptive thermogenesis during dieting
• Less accurate for: obese individuals (overestimates), very lean/muscular (underestimates), elderly, children
• Cannot replace indirect calorimetry for clinical precision

Common Mistakes

• Using "Very Active" multiplier when you exercise only 3x/week (use Moderate)
• Not adjusting as you lose weight — recalculate every 5-10 kg lost
• Eating back all exercise calories reported by fitness trackers (they overestimate by 30-90%)
• Setting deficit too aggressively (>1000 cal) leading to muscle loss and metabolic adaptation
• Ignoring non-exercise activity (walking, fidgeting, standing) which can account for 200-900 cal/day
• Not accounting for weekend overeating which can eliminate a week's deficit

Alternative Metrics

• Indirect calorimetry (clinical gold standard, measures actual O₂ consumption)
• Katch-McArdle formula (uses lean body mass — better for athletes)
• Cunningham equation (for very muscular individuals)
• Adaptive TDEE tracking (use a spreadsheet to track actual intake vs weight change over 4+ weeks)