Calorie Surplus Calculator

Calorie Surplus Calculator determines the daily calorie intake needed to achieve a weight gain 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., 70):

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 Surplus Calculator

The calculator estimates the daily calorie surplus for weight gain using:

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

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

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

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: \( C_{\text{daily}} = \text{TDEE} + C_{\text{surplus}} \)

Where:

\( \Delta W \): Weight gain (kg)
\( C_{\text{total}} \): Total calories for weight gain (kcal)
\( C_{\text{surplus}} \): Daily surplus (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 gain, adjusts BMR for activity, and calculates the required daily calories.

Example Calculation

Sample Input

Current Weight = 70 kg, Goal Weight = 75 kg, Weeks = 10, Activity Level = Moderate (1.55), Current Calories = ?

Step 1: Calculate weight gain: \( \Delta W = 75 – 70 = 5 \, \text{kg} \)

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

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

Step 4: Estimate BMR (assume male, 30 years, 175 cm): \( \text{BMR} = 10 \cdot 70 + 6.25 \cdot 175 – 5 \cdot 30 + 5 \approx 1650 \, \text{kcal/day} \)

Step 5: TDEE: \( \text{TDEE} = 1650 \cdot 1.55 \approx 2557.5 \, \text{kcal/day} \)

Step 6: Total daily calories: \( C_{\text{daily}} = 2557.5 + 550 \approx 3107.5 \, \text{kcal/day} \)

Result: Daily Calories = 3107.5 kcal/day.