Weight Gain Calculator

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Weight Gain Calculator
MaleFemale
Sedentary (office job)Lightly Active (1-3 days/week)Moderately Active (3-5 days/week)Very Active (6-7 days/week)Extra Active (physical job)
0.5 lb (0.25 kg) per week1 lb (0.5 kg) per week2 lbs (1 kg) per week
Daily Calorie Target:

— Calories/day
function calculateWeightGain(){var gender=document.getElementById('gender').value;var age=parseFloat(document.getElementById('age').value);var weightLbs=parseFloat(document.getElementById('weight').value);var ft=parseFloat(document.getElementById('height_ft').value);var inch=parseFloat(document.getElementById('height_in').value);var activity=parseFloat(document.getElementById('activity').value);var surplus=parseFloat(document.getElementById('goal').value);if(isNaN(age)||isNaN(weightLbs)||isNaN(ft)||isNaN(inch)){alert('Please enter valid numbers');return;}var weightKg=weightLbs*0.453592;var heightCm=((ft*12)+inch)*2.54;var bmr=0;if(gender==='male'){bmr=(10*weightKg)+(6.25*heightCm)-(5*age)+5;}else{bmr=(10*weightKg)+(6.25*heightCm)-(5*age)-161;}var tdee=bmr*activity;var target=tdee+surplus;document.getElementById('resultValue').innerHTML=Math.round(target).toLocaleString();if(document.getElementById('steps').checked){var stepsHtml='Step 1: Basal Metabolic Rate (BMR): '+Math.round(bmr)+' kcal
';stepsHtml+='Step 2: Maintenance Calories (TDEE): '+Math.round(tdee)+' kcal
';stepsHtml+='Step 3: Added Surplus: +'+surplus+' kcal
';stepsHtml+='Total Target: '+Math.round(target)+' kcal/day';document.getElementById('stepDetails').innerHTML=stepsHtml;document.getElementById('stepDetails').style.display='block';}else{document.getElementById('stepDetails').style.display='none';}}

How to Use the Weight Gain Calculator

The weight gain calculator is a precise tool designed to help individuals determine the exact number of calories needed to increase body weight in a healthy, controlled manner. Unlike generic calorie counters, this tool accounts for your unique physiology and lifestyle to provide a roadmap for your "bulking" journey.

To get the most accurate results, ensure you provide honest assessments of your activity level and current measurements. Follow these steps:

Biometric Data
Enter your gender, age, weight, and height. These factors determine your Basal Metabolic Rate (BMR), which is the energy your body burns at complete rest.
Activity Level
Select the option that best describes your weekly physical output. This multiplier accounts for calories burned during exercise and daily movement.
Gain Goal
Choose how quickly you wish to gain weight. Medical experts generally recommend a surplus of 250 to 500 calories per day for sustainable muscle growth with minimal fat gain.

How It Works: The Science of Surplus

The weight gain calculator uses the Mifflin-St Jeor Equation, widely considered the most accurate standard for calculating metabolic needs. The process follows a three-step mathematical path:

Total Daily Energy Expenditure (TDEE) = BMR × Activity Factor

  • BMR (Men): (10 × weight in kg) + (6.25 × height in cm) – (5 × age) + 5
  • BMR (Women): (10 × weight in kg) + (6.25 × height in cm) – (5 × age) – 161
  • Activity Factors: Range from 1.2 (Sedentary) to 1.9 (Extra Active).
  • Weight Gain Surplus: To gain 1 pound of body mass, a cumulative surplus of approximately 3,500 calories is required.

Calculation Example

Example Scenario: A 30-year-old male, weighing 160 lbs (72.5 kg), 5'11" (180 cm) tall, with a moderately active lifestyle, wanting to gain 1 lb per week.

Step-by-Step Solution:

  1. Calculate BMR: (10 × 72.5) + (6.25 × 180) – (5 × 30) + 5 = 725 + 1125 – 150 + 5 = 1,705 kcal
  2. Apply Activity Factor: 1,705 × 1.55 (Moderate) = 2,643 kcal (Maintenance)
  3. Add Gain Surplus: 2,643 + 500 (for 1 lb/week) = 3,143 kcal
  4. Final Result: Target 3,143 calories per day to reach the weight gain goal.

Common Questions

Is gaining 2 lbs per week safe?

While a weight gain calculator can show you the calories needed for 2 lbs per week, this is often considered a "dirty bulk." For most people, a gain of 0.5 to 1 lb per week is safer and ensures that a higher percentage of the weight gained is muscle tissue rather than body fat.

What if I don't gain weight at the calculated calories?

Calculators provide estimates. If you don't see the scale move after two weeks, increase your daily intake by 100-200 calories. Genetics and individual metabolic variance can affect the "Maintenance" starting point.

Do I need to change my macronutrients?

Yes, for effective weight gain, calories are king, but protein is the architect. Aim for 0.8 to 1 gram of protein per pound of body weight to ensure the surplus supports muscle synthesis when combined with resistance training.

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