How many calories do I need per day?

Daily calorie needs depend on age, gender, weight, height, and activity level. Average adults need 1,800-2,400 calories/day for women and 2,200-3,000 for men. This calculator uses the Mifflin-St Jeor equation (the most accurate for most people) to calculate your specific Basal Metabolic Rate (BMR), then multiplies by an activity factor to get your Total Daily Energy Expenditure (TDEE).

TDEE (Total Daily Energy Expenditure) is the total number of calories you burn per day, including your basal metabolism, physical activity, and the thermic effect of food. TDEE = BMR × Activity Factor. Activity factors range from 1.2 (sedentary) to 1.9 (very active). TDEE is the most accurate measure of how many calories you need daily.

BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to maintain basic life functions like breathing, circulation, and cell production. For most people, BMR accounts for 60-75% of total daily calorie burn. The Mifflin-St Jeor equation (used by this calculator) is: Men: 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 5. Women: 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161.

What should my macros be?

Recommended macronutrient splits depend on your goal. For weight loss: 40% protein, 35% carbs, 25% fat. For maintenance: 30% protein, 40% carbs, 30% fat. For muscle gain: 30% protein, 45% carbs, 25% fat. Protein is essential for preserving muscle during weight loss and building muscle during gaining phases — aim for at least 0.7-1g per pound of body weight.

✦ Mifflin-St Jeor Formula

Calorie & Macro Calculator

Calculate your daily calorie needs (TDEE), basal metabolic rate (BMR), and optimal protein, carbs, and fat split based on your fitness goals.

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How Are Daily Calories Calculated?

Daily calorie needs are calculated in two steps: first your BMR (calories burned at rest) using the Mifflin-St Jeor equation, then your TDEE by multiplying BMR by an activity factor.

The Mifflin-St Jeor equation (1990) is the most accurate BMR formula for most people. For men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 5. For women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161. TDEE = BMR × activity factor (1.2 to 1.9).

What Are Macronutrients?

Macronutrients are the three main nutrients your body needs in large amounts: protein (4 cal/g), carbohydrates (4 cal/g), and fat (9 cal/g). The optimal ratio depends on your fitness goals.

For weight loss, higher protein (40%) helps preserve muscle mass during a calorie deficit. For maintenance, a balanced split (30/40/30) supports overall health. For muscle gain, higher carbs (45%) fuel intense training while adequate protein (30%) supports muscle synthesis. Fat should never go below 20% of calories as it's essential for hormone production.

How Many Calories Should I Eat to Lose Weight?

To lose weight, eat 500 calories below your TDEE for ~1 lb/week fat loss, or 250 below for ~0.5 lb/week. Never go below 1,200 cal/day (women) or 1,500 cal/day (men) without medical supervision.

A moderate deficit of 500 cal/day is sustainable and preserves muscle mass. Aggressive deficits (750+) may cause muscle loss, metabolic adaptation, and are harder to maintain. Combine a calorie deficit with strength training and adequate protein (0.7-1g per lb body weight) for optimal fat loss while preserving lean mass.

Disclaimer: This calculator provides estimates based on the Mifflin-St Jeor equation and general macronutrient guidelines. Individual needs vary based on metabolism, body composition, medical conditions, and specific fitness goals. Consult a registered dietitian or healthcare provider for personalized nutrition advice, especially if you have dietary restrictions or health conditions.