What Your Numbers Mean
- BMR (Basal Metabolic Rate): Calories your body burns at complete rest — the minimum to keep your heart, lungs, and organs functioning.
- TDEE (Total Daily Energy Expenditure): BMR plus all your daily activity. This is your true maintenance calorie level.
- Calorie Target: Adjusts TDEE based on your goal. Lose = TDEE - 500kcal, Gain = TDEE + 300-500kcal.
- Macros: Protein builds muscle, fat supports hormones, carbs fuel performance. Percentages adjust based on goal.
Frequently Asked Questions
How is BMR calculated?
This calculator uses the Mifflin-St Jeor equation, the most accurate BMR formula for the general population, recommended by the Academy of Nutrition and Dietetics. 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.
What is TDEE and why does it matter?
TDEE (Total Daily Energy Expenditure) is your BMR multiplied by your activity level. It represents the total calories you burn in a day. Eating at your TDEE maintains your weight. Eating below causes weight loss. Eating above causes weight gain.
How many calories should I eat to lose weight?
For sustainable fat loss, we recommend a deficit of ~500 calories below your TDEE. This typically leads to 0.5-1kg (1-2lbs) of fat loss per week. Larger deficits may cause muscle loss and metabolic slowdown.
What macronutrient split should I use?
For weight loss: 40% protein, 30% fat, 30% carbs (higher protein preserves muscle). For maintenance: 30% protein, 30% fat, 40% carbs. For muscle gain: 30% protein, 25% fat, 45% carbs (higher carbs fuel workouts). Adjust based on your individual response.
Can AI calculate my calorie needs?
AI chatbots may attempt to estimate calories, but they frequently hallucinate formulas, apply the wrong activity multipliers, or give inconsistent results across different sessions. This calculator uses the validated Mifflin-St Jeor equation with deterministic math — the same inputs always produce the same correct output, computed entirely in your browser with zero server calls.
Is this calorie calculator accurate?
All calorie formulas are estimates. Mifflin-St Jeor is within ±10% of measured BMR for ~82% of people. Individual metabolism varies based on genetics, hormones, sleep, stress, and muscle mass. Use these numbers as a starting point and adjust based on your real-world results after 2-3 weeks.
Is my data private?
100%. All calculations happen in your browser. We never send your age, weight, height, or gender to any server. No data is stored, tracked, or shared. No signup required.
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