Cal Calculator

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Daily Calorie Needs Calculator

Estimate your daily calorie requirements based on your age, gender, weight, height, and activity level. This calculator uses the Mifflin-St Jeor equation, a widely recognized formula for calculating Basal Metabolic Rate (BMR), and then adjusts it based on your physical activity to determine your Total Daily Energy Expenditure (TDEE).

Sedentary (little or no exercise) Lightly Active (light exercise/sports 1-3 days/week) Moderately Active (moderate exercise/sports 3-5 days/week) Very Active (hard exercise/sports 6-7 days a week) Extra Active (very hard exercise/physical job/training twice a day)
function calculateCalories() { var age = parseFloat(document.getElementById('age').value); var weight = parseFloat(document.getElementById('weight').value); var height = parseFloat(document.getElementById('height').value); var genderMale = document.getElementById('genderMale').checked; var activityFactor = parseFloat(document.getElementById('activityLevel').value); var resultDiv = document.getElementById('calorieResult'); if (isNaN(age) || isNaN(weight) || isNaN(height) || age <= 0 || weight <= 0 || height <= 0) { resultDiv.innerHTML = 'Please enter valid positive numbers for all fields.'; return; } var bmr; if (genderMale) { // Mifflin-St Jeor Equation for Men bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5; } else { // Mifflin-St Jeor Equation for Women bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161; } var tdee = bmr * activityFactor; resultDiv.innerHTML = 'Your estimated daily calorie needs (TDEE) are: ' + tdee.toFixed(0) + ' calories.'; } // Initial calculation on page load for default values window.onload = calculateCalories;

Understanding Your Daily Calorie Needs

Calories are units of energy that your body uses to perform all its functions, from breathing and thinking to exercising and digesting food. Your daily calorie needs, also known as Total Daily Energy Expenditure (TDEE), depend on several factors, including your Basal Metabolic Rate (BMR) and your physical activity level.

Basal Metabolic Rate (BMR)

BMR is the number of calories your body burns at rest to maintain basic life-sustaining functions like circulation, respiration, and cell production. It's the minimum amount of energy required to keep you alive. The Mifflin-St Jeor equation, used in this calculator, is one of the most accurate formulas for estimating BMR.

  • For Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
  • For Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161

Activity Level

Once your BMR is calculated, it's multiplied by an activity factor to account for the calories you burn through daily activities and exercise. The more active you are, the higher your TDEE will be. The activity levels used in this calculator are:

  • Sedentary: Little or no exercise (BMR x 1.2)
  • Lightly Active: Light exercise/sports 1-3 days/week (BMR x 1.375)
  • Moderately Active: Moderate exercise/sports 3-5 days/week (BMR x 1.55)
  • Very Active: Hard exercise/sports 6-7 days a week (BMR x 1.725)
  • Extra Active: Very hard exercise/physical job/training twice a day (BMR x 1.9)

Using Your Calorie Needs for Weight Management

Knowing your TDEE is crucial for setting weight management goals:

  • For Weight Maintenance: Consume approximately your TDEE in calories daily.
  • For Weight Loss: Create a calorie deficit by consuming fewer calories than your TDEE (e.g., 300-500 calories less per day).
  • For Weight Gain: Create a calorie surplus by consuming more calories than your TDEE (e.g., 300-500 calories more per day).

Remember, these are estimates. Individual metabolism can vary, and factors like body composition, genetics, and hormonal balance also play a role. Consult with a healthcare professional or a registered dietitian for personalized advice.

Example Calculation:

Let's calculate the daily calorie needs for a 30-year-old female, weighing 65 kg, 165 cm tall, with a moderately active lifestyle:

  • Age: 30 years
  • Gender: Female
  • Weight: 65 kg
  • Height: 165 cm
  • Activity Level: Moderately Active (factor 1.55)

1. Calculate BMR (Female):
BMR = (10 × 65) + (6.25 × 165) – (5 × 30) – 161
BMR = 650 + 1031.25 – 150 – 161
BMR = 1370.25 calories

2. Calculate TDEE:
TDEE = BMR × Activity Factor
TDEE = 1370.25 × 1.55
TDEE = 2123.8875 calories

So, this individual would need approximately 2124 calories per day to maintain her current weight.

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