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Calorie Calculator

Estimate your daily calorie needs using the Mifflin-St Jeor equation. See your BMR, TDEE, and calorie targets for weight loss or gain.

Disclaimer: This calculator is for informational purposes only. Consult a healthcare provider for medical advice.
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Enter your details and activity level, then click Calculate Calories to see your daily needs.

How Calorie Calculations Work

The Mifflin-St Jeor Equation

This calculator uses the Mifflin-St Jeor equation, which is widely regarded as the most reliable formula for estimating Basal Metabolic Rate (BMR). Developed in 1990, it replaced older formulas like the Harris-Benedict equation and has been validated in numerous clinical studies across diverse populations.

How BMR Is Calculated

The Mifflin-St Jeor formula uses your weight, height, age, and sex to estimate BMR:

  • **Men:** BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) + 5
  • **Women:** BMR = (10 x weight in kg) + (6.25 x height in cm) - (5 x age in years) - 161

BMR represents the calories your body burns at complete rest over 24 hours. This includes energy for breathing, blood circulation, brain function, and cellular repair. For most people, BMR accounts for 60 to 75 percent of total daily energy expenditure.

From BMR to TDEE

Your Total Daily Energy Expenditure (TDEE) is calculated by multiplying your BMR by an activity multiplier that reflects your overall daily movement and exercise habits:

  • **Sedentary (x1.2):** Desk job, little to no exercise
  • **Lightly active (x1.375):** Light exercise one to three days per week
  • **Moderately active (x1.55):** Moderate exercise three to five days per week
  • **Very active (x1.725):** Hard exercise six to seven days per week
  • **Extra active (x1.9):** Very intense exercise or a physically demanding job

Setting Calorie Targets

Once you know your TDEE, you can set targets based on your goals. To lose weight, eat below your TDEE, typically 500 calories less per day for about one pound of loss per week. To gain weight, eat above your TDEE by a similar margin. For maintenance, match your calorie intake to your TDEE and monitor your weight over time, adjusting as needed.

Frequently asked questions

Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day, including all physical activity and bodily functions. It is calculated by multiplying your Basal Metabolic Rate (BMR) by an activity factor that reflects how active you are throughout the day. TDEE gives you a practical target for daily calorie intake to maintain your current weight.

BMR (Basal Metabolic Rate) is the number of calories your body needs at complete rest to maintain basic life-sustaining functions such as breathing, circulation, and cell production. TDEE builds on BMR by adding the calories burned through daily activity and exercise. Think of BMR as your baseline energy cost and TDEE as your total daily energy budget including movement.

A deficit of 500 calories per day below your TDEE is commonly recommended, which translates to roughly one pound of weight loss per week. A more aggressive deficit of 750 to 1,000 calories per day can lead to faster results but may be harder to sustain and could affect energy levels, muscle mass, and nutrient intake. It is generally best to aim for a moderate deficit and adjust based on your progress.

The Mifflin-St Jeor equation is considered one of the most accurate predictive equations for estimating BMR, with studies showing it falls within 10% of actual measured values for most people. However, individual variation exists due to factors like genetics, body composition, hormonal status, and metabolic adaptation. Use the results as a starting point and adjust based on real-world results over two to four weeks.

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