Calorie Calculator

Find your daily calorie needs using the Mifflin-St Jeor equation — the gold standard for BMR estimation.

Gender

Age

years

Weight

Height

Activity Level

Basal Metabolic Rate (BMR)

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calories/day at rest

Maintenance Calories (TDEE)

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calories/day to maintain weight

Calorie Targets by Goal

Extreme Weight Loss

Lose ~1 kg / 2 lbs per week

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Mild Weight Loss

Lose ~0.5 kg / 1 lb per week

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Maintain Weight

TDEE — current energy balance

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Mild Weight Gain

Gain ~0.25 kg / 0.5 lbs per week

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Weight Gain (Bulk)

Gain ~0.5 kg / 1 lb per week

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Recommended Macros (at Maintenance)

Protein—

Carbohydrates—

Fat—

Learn

Understanding Calories, BMR, and TDEE

A calorie is a unit of energy. Your body needs a certain number of calories every day to maintain its current weight — this is called your Total Daily Energy Expenditure (TDEE). Eat less than your TDEE to lose weight; eat more to gain weight.

Our calculator uses the Mifflin-St Jeor equation, widely considered the most accurate formula for estimating Basal Metabolic Rate (BMR) in both men and women, validated across multiple clinical studies published in the American Journal of Clinical Nutrition.

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BMR vs TDEE

BMR is your calorie burn at complete rest — just to keep organs functioning. TDEE multiplies BMR by an activity factor to account for exercise and daily movement. Most people's TDEE is 1.2× to 1.9× their BMR.

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Calories In vs Out

Weight management is fundamentally about energy balance. A consistent 500 calorie/day deficit leads to roughly 0.5 kg (1 lb) loss per week. Extreme deficits (>1000 cal/day) can cause muscle loss and metabolic adaptation.

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Macronutrients Matter

Not all calories are equal metabolically. Protein (4 kcal/g) preserves muscle and increases satiety. Carbohydrates (4 kcal/g) fuel workouts. Fat (9 kcal/g) supports hormones. Optimal ratios depend on your specific goals.

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Metabolic Adaptation

Extended calorie restriction causes the body to adapt by lowering BMR (adaptive thermogenesis). This is why diet breaks and refeed days — eating at maintenance — are effective strategies for long-term fat loss without plateaus.

FAQ

Frequently Asked Questions

How accurate is the Mifflin-St Jeor equation?

The Mifflin-St Jeor equation is accurate within ±10% for most people. It outperforms the older Harris-Benedict equation in clinical validation studies. However, individual metabolic rates vary based on genetics, muscle mass, hormones (thyroid), and medications. Use this as a starting estimate and adjust based on 2–4 weeks of tracked results.

How many calories should I eat to lose weight?

A 500 calorie/day deficit from your TDEE yields roughly 0.5 kg (1 lb) of fat loss per week. A 1,000 cal/day deficit ≈ 1 kg/week. However, most experts recommend not going below 1,200 calories/day for women or 1,500/day for men without medical supervision, as this risks nutritional deficiencies and muscle loss.

What is the recommended macro split?

A commonly recommended balanced split is 30% protein, 45% carbohydrates, 25% fat — which is what this calculator shows. However: athletes may want higher carbs (50-60%), those on ketogenic diets want very low carbs (<5%), and high-protein dieters target 35-40% protein. There's no universally "optimal" macro split — the best one is the one you can maintain consistently.

Why am I not losing weight despite a calorie deficit?

Common reasons include: underestimating calorie intake (studies show people underreport by 30-50%), overestimating exercise calories burned, water retention masking fat loss, stress-induced cortisol elevation, poor sleep affecting hunger hormones (ghrelin/leptin), and metabolic adaptation. Track food accurately for 2 weeks using a scale before adjusting calories.