Calorie Calculator

Frequently Asked Questions

What is BMR (Basal Metabolic Rate)?

BMR is the number of calories your body burns at complete rest to maintain vital functions — breathing, circulation, cell production, and organ function. It represents 60–70% of your total daily calorie expenditure. This calculator uses the Mifflin-St Jeor equation, the most accurate BMR formula for most people.

What is TDEE (Total Daily Energy Expenditure)?

TDEE is BMR multiplied by an activity multiplier that accounts for physical activity. It represents how many calories you burn in a typical day. To maintain your current weight, eat approximately equal to your TDEE. To lose weight, eat less than your TDEE; to gain muscle, eat slightly more.

How accurate is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation is the most validated BMR formula for adults of healthy weight, predicting BMR within ±10% for most people. It is less accurate for very muscular individuals (underestimates) and those with obesity (overestimates). Actual calorie needs can only be confirmed through metabolic testing.

How many calories should I eat to lose weight?

A 500 calorie/day deficit below TDEE creates approximately a 1 pound (0.45 kg) per week loss — the commonly recommended rate. A 250 calorie deficit creates 0.5 lb/week loss. Going below 1,200 calories/day (women) or 1,500/day (men) is not recommended without medical supervision.

What is the difference between calories and kilocalories?

In food/nutrition, "calorie" always means kilocalorie (kcal) — 1,000 thermodynamic calories. When a food label says "200 calories," it means 200 kcal. The notation Calorie (uppercase C) technically means kcal, but in everyday use, "calorie" and "kcal" are used interchangeably for food energy.

What activity level should I select?

Sedentary: desk job, minimal walking. Lightly active: walking 1–3 days/week or light exercise. Moderately active: cardio 3–5 days/week or a physically moderate job. Very active: intense training 6–7 days/week or a physical job. Extra active: athletic training twice daily or very heavy manual labor.

What are macros and how are the percentages calculated?

Macronutrients (macros) are protein, carbohydrates, and fat — the three sources of calories. The suggested split (30% protein, 45% carbs, 25% fat) is a moderate balanced ratio. Protein and carbs provide 4 calories/gram; fat provides 9 calories/gram. Adjusting these ratios for your goals (e.g. higher protein for muscle gain, lower carbs for keto) changes the grams shown.