Calorie Calculator

Use our free calorie calculator to get an instant, science-backed result in under 30 seconds. All calculations run entirely in your browser — no data leaves your device, no account required.

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Your Fitness Goal

What Is Calorie Calculator?

A calorie calculator is a science-backed tool designed to estimate your daily energy target based on your physical stats, activity level, and specific fitness goal. In physics and nutrition, a calorie is a unit of energy. A calorie target determines whether your body stores fat (caloric surplus), burns fat (caloric deficit), or remains at its current weight (caloric maintenance).

Your calorie target is derived directly from your Total Daily Energy Expenditure (TDEE). By inputting your age, height, weight, and biological sex, the calculator first determines your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation. It then applies an activity multiplier to estimate your total daily burn. Finally, the calculator adjusts this baseline up or down depending on whether you want to lose weight or build muscle.

Losing weight sustainably requires a calorie deficit, which means consuming fewer calories than you burn. A deficit of 500 calories per day will result in approximately 0.5 kg (1 lb) of fat loss per week. Conversely, building lean muscle tissue efficiently requires a calorie surplus (consuming more calories than you burn) alongside strength training to provide the body with the raw materials needed for muscle synthesis.

Managing your weight by counting calories is the most reliable approach because it aligns with the first law of thermodynamics: energy cannot be created or destroyed, only transformed. While food quality is critical for health and satiety, energy balance is the ultimate governor of weight change.

How to Calculate — The Mifflin-St Jeor + Goal Adjustment Formula

Our calculator determines your target daily calories in a three-step sequence, utilizing the Mifflin-St Jeor equation for resting energy expenditure.

The Calorie Target Equations

Step 1: Calculate BMR (Mifflin-St Jeor)
  Men:   BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
  Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161

Step 2: Calculate TDEE (Maintenance)
  TDEE = BMR × Activity Multiplier (1.2 to 1.9)

Step 3: Adjust for Goal
  Weight Loss (Deficit):       TDEE − 500 kcal/day
  Weight Maintenance:          TDEE
  Muscle Building (Surplus):   TDEE + 300 kcal/day

Source: Mifflin MD, St Jeor ST, et al. (1990). "A new predictive equation for resting energy expenditure in healthy individuals." American Journal of Clinical Nutrition.

Step-by-Step Example

Let's look at a 30-year-old male who is 180 cm tall, weighs 80 kg, works a desk job, and goes to the gym 3–5 days a week (Moderately Active, multiplier ×1.55). His goal is weight loss:

BMR Calculation: (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 800 + 1125 − 150 + 5 = 1,780 kcal.
TDEE Calculation: BMR (1,780) × Activity Multiplier (1.55) = 2,759 kcal. This is his maintenance level.
Deficit Adjustment: Maintenance (2,759) − Deficit (500) = 2,259 kcal/day. This is his daily target.

What Does Your Result Mean?

Understanding how your calorie target aligns with your goals is essential for managing expectations and ensuring a healthy rate of progress.

Calorie Targets and Expected Outcomes

Goal Setting	Calorie Adjustment	Healthy Rate of Change	Primary Focus
Weight Loss (Deficit)	TDEE − 500 calories	Lose 0.3 to 0.5 kg per week	Preserve muscle mass by keeping protein high while burning fat.
Recomposition (Maintenance)	TDEE (0 adjustment)	Weight stays stable; fat down, muscle up	Ideal for beginners or those returning to training. Slow but steady.
Lean Bulk (Surplus)	TDEE + 300 calories	Gain 0.2 to 0.3 kg per week	Provide extra energy for muscle repair while minimizing fat storage.

Adjusting Your Intake Over Time

Your calculated calorie target is an estimate. Individual metabolisms vary based on genetics, muscle density, and daily steps (NEAT). Track your daily calorie intake and weigh yourself first thing in the morning. Take the weekly average of your weight. If after 3 weeks your weight has not changed in the desired direction, adjust your calorie target by 100–150 calories up or down.

Frequently Asked Questions

How many calories should I eat to lose weight?

To lose weight, you must create a calorie deficit by consuming fewer calories than you burn. A safe and sustainable target is 300 to 500 calories below your TDEE (Total Daily Energy Expenditure). This target generally results in a loss of about 0.3 to 0.5 kg (0.5 to 1 lb) of body fat per week. Consuming fewer than 1,200 calories per day for women or 1,500 for men is not recommended without medical supervision.

What is a calorie deficit?

A calorie deficit occurs when your energy intake (calories consumed from food and drinks) is less than your energy output (calories burned through your BMR, daily movement, and active exercise). When in a deficit, your body is forced to mobilize and burn stored body fat to meet its energy demands, resulting in weight loss.

How many calories do I burn at rest?

The calories you burn at complete rest is represented by your Basal Metabolic Rate (BMR). For most average adults, this resting metabolic baseline ranges from 1,200 to 1,800 calories per day. This energy is used to power your organs, regulate body temperature, and keep tissues healthy. You can calculate your exact resting baseline using our built-in BMR calculator.

Should I eat less than my BMR for faster weight loss?

No. Eating below your BMR is generally counterproductive and unsafe. Consuming too few calories signals your body to slow down its metabolism to conserve energy, leading to significant muscle loss, fatigue, hormone dysregulation, and nutrient deficiencies. Always target a deficit relative to your TDEE while keeping intake close to or above your BMR.

How does muscle mass affect my calorie needs?

Muscle tissue is highly active metabolically, meaning it burns more calories at rest than fat tissue. Every kilogram of muscle tissue burns roughly 10–13 calories per day, whereas fat tissue burns only about 4–5 calories. By building lean muscle through strength training, you increase your resting metabolic rate and raise your daily calorie target.

How do I track my calorie intake accurately?

To track accurately, use a digital kitchen scale to weigh your food in grams before cooking, as volume measurements (like cups or spoons) are highly inaccurate. Log everything you eat and drink in a tracking app, making sure to include cooking oils, sauces, salad dressings, and liquid calories, which are common sources of hidden calories.

Why has my weight loss stalled on the same calories?

As you lose weight, your body becomes smaller and requires less energy to move. This decreases your BMR and TDEE. Additionally, your body adapts by slightly reducing unconscious movements (NEAT). If weight loss has stalled for more than 3 consecutive weeks, you likely need to recalculate your calorie target based on your new weight.

Does the source of calories matter for fat loss?

For pure weight loss, total calorie intake is the primary driver (thermodynamics). However, for body composition (losing fat instead of muscle), the source of calories matters. Consuming adequate protein preserves muscle mass in a deficit, while eating whole foods instead of processed foods increases the thermic effect of food (TEF), helping you burn more calories naturally.

Now that you have your calorie result, use these tools to build a complete picture of your health metrics.

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Medically & Scientifically Reviewed Calculations and guidelines on this page adhere to peer-reviewed equations (Mifflin-St Jeor + Goal Adjustment) published by the American Journal of Clinical Nutrition, ACSM, and World Health Organization. Independently reviewed by the CalaiFitness Scientific Advisory Board.

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