Callorie Calculator

Daily Calorie Needs Calculator

function calculateCalories() { var age = parseFloat(document.getElementById('age').value); var gender = document.getElementById('gender').value; var weight = parseFloat(document.getElementById('weight').value); var weightUnit = document.getElementById('weightUnit').value; var height = parseFloat(document.getElementById('height').value); var heightUnit = document.getElementById('heightUnit').value; var activityLevel = document.getElementById('activityLevel').value; var goal = document.getElementById('goal').value; var resultDiv = document.getElementById('result'); // Input validation if (isNaN(age) || age <= 0 || isNaN(weight) || weight <= 0 || isNaN(height) || height <= 0) { resultDiv.innerHTML = 'Please enter valid positive numbers for age, weight, and height.'; resultDiv.style.display = 'block'; return; } // Unit conversions var weight_kg = (weightUnit === 'lbs') ? weight * 0.453592 : weight; var height_cm = (heightUnit === 'inches') ? height * 2.54 : height; // Mifflin-St Jeor Equation for BMR var bmr; if (gender === 'male') { bmr = (10 * weight_kg) + (6.25 * height_cm) – (5 * age) + 5; } else { // female bmr = (10 * weight_kg) + (6.25 * height_cm) – (5 * age) – 161; } // Activity Factor var activityFactor; switch (activityLevel) { case 'sedentary': activityFactor = 1.2; break; case 'lightlyActive': activityFactor = 1.375; break; case 'moderatelyActive': activityFactor = 1.55; break; case 'veryActive': activityFactor = 1.725; break; case 'extraActive': activityFactor = 1.9; break; default: activityFactor = 1.2; // Default to sedentary } // Calculate TDEE (Total Daily Energy Expenditure) var tdee = bmr * activityFactor; // Adjust for Goal var targetCalories = tdee; var goalDescription = ""; switch (goal) { case 'maintain': goalDescription = "to maintain your current weight"; break; case 'mildLoss': targetCalories -= 250; // ~0.25 kg / 0.5 lbs per week goalDescription = "for mild weight loss (approx. 0.25 kg / 0.5 lbs per week)"; break; case 'moderateLoss': targetCalories -= 500; // ~0.5 kg / 1 lbs per week goalDescription = "for moderate weight loss (approx. 0.5 kg / 1 lbs per week)"; break; case 'extremeLoss': targetCalories -= 1000; // ~1 kg / 2 lbs per week goalDescription = "for extreme weight loss (approx. 1 kg / 2 lbs per week)"; break; case 'mildGain': targetCalories += 250; // ~0.25 kg / 0.5 lbs per week goalDescription = "for mild weight gain (approx. 0.25 kg / 0.5 lbs per week)"; break; case 'moderateGain': targetCalories += 500; // ~0.5 kg / 1 lbs per week goalDescription = "for moderate weight gain (approx. 0.5 kg / 1 lbs per week)"; break; } // Display results resultDiv.innerHTML = '

Your Calorie Needs:

' + 'Your Basal Metabolic Rate (BMR): ' + bmr.toFixed(0) + ' calories/day' + 'Your Total Daily Energy Expenditure (TDEE): ' + tdee.toFixed(0) + ' calories/day' + 'To achieve your goal ' + goalDescription + ', you should aim for approximately ' + targetCalories.toFixed(0) + ' calories/day.' + 'Note: These are estimates. Individual needs may vary.'; resultDiv.style.display = 'block'; }

Understanding Your Daily Calorie Needs

A calorie calculator is a tool designed to estimate the number of calories your body needs daily to maintain, lose, or gain weight. It takes into account several factors unique to you, providing a personalized estimate of your energy requirements.

How Does It Work?

Our calculator uses the widely accepted Mifflin-St Jeor Equation to determine your Basal Metabolic Rate (BMR), and then applies an activity factor to calculate your Total Daily Energy Expenditure (TDEE). Finally, it adjusts this number based on your weight goal.

1. Basal Metabolic Rate (BMR)

Your BMR is the number of calories your body burns at rest to perform basic life-sustaining functions like breathing, circulation, cell production, and nutrient processing. It's the minimum energy required to keep your body functioning if you were to do nothing but rest for 24 hours.

• 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

2. Total Daily Energy Expenditure (TDEE)

Your TDEE is your BMR multiplied by an activity factor. This factor accounts for the calories you burn through physical activity, including exercise and non-exercise activity thermogenesis (NEAT). The more active you are, the higher your TDEE.

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

3. Adjusting for Your Goal

Once your TDEE is calculated, we adjust it based on your weight goal:

• Maintain Weight: Eat your TDEE.
• Weight Loss: To lose approximately 0.5 kg (1 lb) per week, a deficit of 500 calories per day is generally recommended. Our calculator adjusts for mild (250 cal), moderate (500 cal), and extreme (1000 cal) deficits.
• Weight Gain: To gain approximately 0.5 kg (1 lb) per week, a surplus of 500 calories per day is generally recommended. Our calculator adjusts for mild (250 cal) and moderate (500 cal) surpluses.

Realistic Examples

Example 1: Weight Loss Goal

Let's consider a 30-year-old female, weighing 68 kg (150 lbs), standing 165 cm (65 inches) tall, with a moderately active lifestyle, aiming for moderate weight loss (1 lb/week).

• BMR: (10 * 68) + (6.25 * 165) – (5 * 30) – 161 = 680 + 1031.25 – 150 – 161 = 1400.25 calories
• TDEE: 1400.25 * 1.55 (moderately active) = 2170.39 calories
• Target Calories for Moderate Loss: 2170.39 – 500 = 1670.39 calories

This individual would need approximately 1670 calories per day to achieve a moderate weight loss.

Example 2: Weight Maintenance Goal

Consider a 40-year-old male, weighing 81.6 kg (180 lbs), standing 178 cm (70 inches) tall, with a lightly active lifestyle, aiming to maintain his current weight.

• BMR: (10 * 81.6) + (6.25 * 178) – (5 * 40) + 5 = 816 + 1112.5 – 200 + 5 = 1733.5 calories
• TDEE: 1733.5 * 1.375 (lightly active) = 2383.56 calories
• Target Calories for Maintenance: 2383.56 calories

This individual would need approximately 2384 calories per day to maintain his current weight.

Important Considerations

While this calculator provides a good estimate, individual metabolic rates can vary. Factors like genetics, body composition (muscle vs. fat), hormonal balance, and certain medical conditions can influence your actual calorie needs. Always consult with a healthcare professional or a registered dietitian for personalized advice, especially if you have specific health concerns or significant weight goals.