How this Calorie Calculator Works
This calculator estimates the number of calories you need to eat daily to maintain, lose, or gain weight. It uses the Mifflin-St Jeor Equation, which is considered one of the most accurate methods for estimating Basal Metabolic Rate (BMR).
Step 1: Calculating BMR
First, we calculate your BMR—the energy your body needs just to function at rest.
Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Step 2: Activity Multiplier
We multiply your BMR by an activity factor to find your Total Daily Energy Expenditure (TDEE):
- Sedentary (x 1.2): Little or no exercise, desk job.
- Lightly Active (x 1.375): Light exercise or sports 1-3 days a week.
- Moderately Active (x 1.55): Moderate exercise or sports 3-5 days a week.
- Very Active (x 1.725): Hard exercise or sports 6-7 days a week.
- Super Active (x 1.9): Very hard exercise, physical job, or training twice a day.
Weight Loss & Gain Logic
Once your maintenance calories (TDEE) are established, the calculator applies standard deficits and surpluses:
- Mild Weight Loss: Subtracts 250 calories/day (approx. 0.25 kg or 0.5 lb loss per week).
- Weight Loss: Subtracts 500 calories/day (approx. 0.5 kg or 1 lb loss per week).
- Weight Gain: Adds 250-500 calories/day to support muscle growth or mass gain.
Step-by-Step Instructions
- Select Units: Choose Metric (kg/cm) or Imperial (lb/in).
- Enter Details: Input your current age, gender, weight, and height.
- Choose Activity Level: Be honest about your daily activity. Most people with office jobs fall into "Sedentary" or "Lightly Active" unless they train deliberately.
- Review Targets: See the exact calorie numbers required to reach your specific weight goal.