Calorie Calculator (TDEE)

The Calorie Calculator determines your Total Daily Energy Expenditure (TDEE)—the exact number of calories your body burns in a day. By understanding your TDEE, you can set precise daily calorie targets to safely lose weight, maintain your current physique, or build muscle.

How It Works

The calculator uses your age, gender, height, and weight to calculate your Basal Metabolic Rate (BMR)—the calories your body needs just to stay alive at rest. It then multiplies your BMR by an Activity Factor (representing your daily movement and exercise) to calculate your final TDEE.

Formula & Calculation Logic

This calculator uses the Mifflin-St Jeor Equation, which clinical studies have shown to be the most accurate predictive equation for resting metabolic rate in healthy adults.

Step 1: Calculate Basal Metabolic Rate (BMR)

• For Men: $\text{BMR} = (10 \times \text{weight in kg}) + (6.25 \times \text{height in cm}) - (5 \times \text{age in years}) + 5$
• For Women: $\text{BMR} = (10 \times \text{weight in kg}) + (6.25 \times \text{height in cm}) - (5 \times \text{age in years}) - 161$

Step 2: Calculate TDEE (Maintenance Calories) $\text{TDEE} = \text{BMR} \times \text{Activity Multiplier}$

Activity Multipliers:

• Sedentary (little to no exercise): 1.2
• Lightly Active (light exercise 1-3 days/week): 1.375
• Moderately Active (moderate exercise 3-5 days/week): 1.55
• Very Active (hard exercise 6-7 days/week): 1.725
• Extra Active (very hard exercise & physical job): 1.9

Input Parameters & Units

| Parameter | Expected Unit | Typical Range | Description | |---|---|---|---| | Body Weight | kg or lbs | 30 to 250 kg | Current body weight in light clothing. | | Height | cm or ft/in | 100 to 250 cm | Standing height measured without shoes. | | Age | Years | 15 to 99 Years | Biological age for metabolic calculations. | | Gender | Option | Male / Female | Physiological baseline for the Mifflin-St Jeor formula. | | Activity Level | Multiplier | Sedentary to Very Active | Your average daily movement and exercise volume. |

Worked Example

Let's calculate the calorie needs for a 30-year-old male who weighs 80 kg, is 180 cm tall, and exercises moderately (3-5 days a week).

Calculation Steps:

1. Calculate BMR: $(10 \times 80) + (6.25 \times 180) - (5 \times 30) + 5$ $800 + 1125 - 150 + 5 = 1780 \text{ calories/day}$
2. Apply Activity Multiplier: $1780 \times 1.55 \text{ (Moderate Activity)} = 2759 \text{ calories/day}$

Result: This individual needs to consume 2,759 calories per day to maintain their current weight (TDEE). To lose 1 pound per week (a 500-calorie daily deficit), their target would be 2,259 calories per day.

Result Interpretation

• Maintenance: Consuming your TDEE will keep your weight exactly the same.
• Weight Loss (Cutting): To lose weight, you must eat fewer calories than your TDEE. A common target is a 500-calorie deficit per day, which generally results in about 1 pound (0.45 kg) of fat loss per week.
• Weight Gain (Bulking): To build muscle, you need to eat more calories than your TDEE. A surplus of 250 to 500 calories per day is recommended for steady muscle growth with minimal fat gain.

Practical Considerations & Limitations

• Estimates Only: The Mifflin-St Jeor equation provides a highly educated estimate, not an absolute truth. Your actual metabolism may vary based on genetics, muscle mass, and medical conditions (like thyroid issues).
• Activity Level Overestimation: People frequently overestimate their activity level. If you work a desk job but go to the gym for 45 minutes a day, you are generally considered "Lightly Active," not "Very Active."
• Adaptation: As you lose weight, your BMR decreases because a smaller body requires fewer calories to maintain. You must recalculate your TDEE periodically as your weight drops.

Frequently Asked Questions

What are Macros?

"Macros" (macronutrients) are the three main providers of calories in your diet: Protein (4 calories/gram), Carbohydrates (4 calories/gram), and Fats (9 calories/gram). Once you know your calorie target, you divide those calories among the three macros based on your fitness goals.

Is a 1,200-calorie diet safe?

For most adults, 1,200 calories is too low and falls below their BMR (the energy needed for basic organ function). Severe calorie restriction can lead to muscle loss, nutrient deficiencies, and metabolic slowdown. Always consult a doctor before starting a very low-calorie diet.

Are my inputs private?

Yes. Your age, height, and weight are processed entirely within your local browser. No personal health data is saved or transmitted.