Calorie Deficit Calculator

Calorie Deficit Calculator determines the daily calorie intake needed to achieve a weight loss goal, based on current weight, goal weight, time frame, activity level, and optional current calorie intake.

Enter values (leave the unknown field blank):

Current Weight (kg, e.g., 80):

Goal Weight (kg, e.g., 75):

Time Frame (weeks, e.g., 10):

Activity Level:

Current Daily Calories (kcal, e.g., 2000, optional):

Methodology Used in Calorie Deficit Calculator

The calculator estimates the daily calorie deficit for weight loss using:

1. Weight loss: \\( \Delta W = \text{Current Weight} – \text{Goal Weight} \\)

2. Total calories needed: \\( C_{\text{total}} = \Delta W \cdot 7700 \\)

3. Daily deficit: \\( C_{\text{deficit}} = \frac{C_{\text{total}}}{\text{Weeks} \cdot 7} \\)

4. BMR (Mifflin-St Jeor): \\( \text{BMR} = 10 \cdot \text{Weight} + 6.25 \cdot \text{Height} – 5 \cdot \text{Age} + 5 \\) (men) or \\( -161 \\) (women)

5. TDEE: \\( \text{TDEE} = \text{BMR} \cdot \text{Activity Multiplier} \\)

6. Total daily calories: \\( C_{\text{daily}} = \text{TDEE} – C_{\text{deficit}} \\)

Where:

\\( \Delta W \\): Weight loss (kg)
\\( C_{\text{total}} \\): Total calories for weight loss (kcal)
\\( C_{\text{deficit}} \\): Daily deficit (kcal/day)
\\( \text{BMR} \\): Basal Metabolic Rate (kcal/day)
\\( \text{TDEE} \\): Total Daily Energy Expenditure (kcal/day)

The solver uses 7700 kcal/kg for weight loss, adjusts BMR for activity, and calculates the required daily calories.

Example Calculation

Sample Input

Current Weight = 80 kg, Goal Weight = 75 kg, Weeks = 10, Activity Level = Moderate (1.55), Current Calories = ?

Step 1: Calculate weight loss: \\( \Delta W = 80 – 75 = 5 \, \text{kg} \\)

Step 2: Total calories: \\( C_{\text{total}} = 5 \cdot 7700 = 38500 \, \text{kcal} \\)

Step 3: Daily deficit: \\( C_{\text{deficit}} = \frac{38500}{10 \cdot 7} \approx 550 \, \text{kcal/day} \\)

Step 4: Estimate BMR (assume male, 30 years, 175 cm): \\( \text{BMR} = 10 \cdot 80 + 6.25 \cdot 175 – 5 \cdot 30 + 5 \approx 1750 \, \text{kcal/day} \\)

Step 5: TDEE: \\( \text{TDEE} = 1750 \cdot 1.55 \approx 2712.5 \, \text{kcal/day} \\)

Step 6: Total daily calories: \\( C_{\text{daily}} = 2712.5 – 550 \approx 2162.5 \, \text{kcal/day} \\)

Result: Daily Calories = 2162.5 kcal/day.