Calculating Calories

Daily Calorie Needs Calculator

Estimate your daily calorie requirements to maintain, lose, or gain weight using the Mifflin-St Jeor equation, which is widely recognized for its accuracy.

(1 lb = 0.453592 kg)

(1 inch = 2.54 cm)

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) Extremely Active (very hard exercise/physical job)

Maintain Weight Mild Weight Loss (approx. 0.25 kg/week) Weight Loss (approx. 0.5 kg/week) Extreme Weight Loss (approx. 1 kg/week) Mild Weight Gain (approx. 0.25 kg/week) Weight Gain (approx. 0.5 kg/week) Extreme Weight Gain (approx. 1 kg/week)

function calculateCalories() { var age = parseFloat(document.getElementById('age').value); var gender = document.querySelector('input[name="gender"]:checked').value; var weight = parseFloat(document.getElementById('weight').value); var height = parseFloat(document.getElementById('height').value); var activityLevel = document.getElementById('activityLevel').value; var weightGoal = document.getElementById('weightGoal').value; var resultDiv = document.getElementById('calorieResult'); // Input validation if (isNaN(age) || age <= 0 || isNaN(weight) || weight <= 0 || isNaN(height) || height <= 0) { resultDiv.style.display = 'block'; resultDiv.style.backgroundColor = '#f8d7da'; resultDiv.style.borderColor = '#f5c6cb'; resultDiv.style.color = '#721c24'; resultDiv.innerHTML = 'Please enter valid positive numbers for Age, Weight, and Height.'; return; } var bmr; // Basal Metabolic Rate // Mifflin-St Jeor Equation if (gender === 'male') { bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5; } else { // female bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161; } var tdee; // Total Daily Energy Expenditure // Activity Level Multiplier switch (activityLevel) { case 'sedentary': tdee = bmr * 1.2; break; case 'lightlyActive': tdee = bmr * 1.375; break; case 'moderatelyActive': tdee = bmr * 1.55; break; case 'veryActive': tdee = bmr * 1.725; break; case 'extremelyActive': tdee = bmr * 1.9; break; default: tdee = bmr * 1.55; // Default to moderately active if somehow not selected } var finalCalories = tdee; // Adjust for Weight Goal switch (weightGoal) { case 'maintain': // No adjustment needed break; case 'mildLoss': finalCalories -= 250; // ~0.25 kg/week loss break; case 'loss': finalCalories -= 500; // ~0.5 kg/week loss break; case 'extremeLoss': finalCalories -= 1000; // ~1 kg/week loss break; case 'mildGain': finalCalories += 250; // ~0.25 kg/week gain break; case 'gain': finalCalories += 500; // ~0.5 kg/week gain break; case 'extremeGain': finalCalories += 1000; // ~1 kg/week gain break; } resultDiv.style.display = 'block'; resultDiv.style.backgroundColor = '#e9f7ee'; resultDiv.style.borderColor = '#d4edda'; resultDiv.style.color = '#155724'; resultDiv.innerHTML = 'Your estimated daily calorie needs: ' + Math.round(finalCalories) + ' calories'; }

Understanding Your Daily Calorie Needs

Calculating your daily calorie needs is a fundamental step in managing your weight, whether you aim to lose, maintain, or gain. Calories are units of energy that your body uses to perform all its functions, from breathing and thinking to exercising and digesting food. This calculator uses the widely accepted Mifflin-St Jeor equation to provide a personalized estimate.

Basal Metabolic Rate (BMR)

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain basic life-sustaining functions. This includes processes like breathing, circulation, cell production, nutrient processing, and temperature regulation. It's the minimum amount of energy your body needs to simply exist. Factors like age, gender, weight, and height significantly influence your BMR.

• Age: BMR generally decreases with age as muscle mass tends to decline.
• Gender: Men typically have a higher BMR than women due to a higher average muscle mass.
• Weight & Height: Larger and taller individuals generally have a higher BMR because they have more body mass to maintain.

Total Daily Energy Expenditure (TDEE)

While BMR accounts for your resting energy needs, your Total Daily Energy Expenditure (TDEE) includes the calories you burn through all activities throughout the day. This encompasses your BMR plus the energy expended through physical activity and the thermic effect of food (the energy used to digest and absorb nutrients).

The calculator adjusts your BMR based on your selected activity level:

• Sedentary: Little or no exercise.
• Lightly Active: Light exercise or sports 1-3 days per week.
• Moderately Active: Moderate exercise or sports 3-5 days per week.
• Very Active: Hard exercise or sports 6-7 days a week.
• Extremely Active: Very hard exercise, a physically demanding job, or training twice a day.

Setting Your Weight Goal

Once your TDEE is estimated, the calculator further refines your calorie target based on your weight goal:

• Maintain Weight: Your calorie intake should roughly match your TDEE.
• Weight Loss: To lose weight, you need to create a calorie deficit, meaning you consume fewer calories than your TDEE. A deficit of 500 calories per day typically leads to a loss of about 0.5 kg (1 pound) per week.
• Weight Gain: To gain weight, you need a calorie surplus, consuming more calories than your TDEE. A surplus of 500 calories per day typically leads to a gain of about 0.5 kg (1 pound) per week.

The calculator offers options for mild, moderate, and extreme weight loss or gain, corresponding to different calorie adjustments. It's generally recommended to aim for gradual changes (mild or moderate) for sustainable and healthy results.

Important Considerations

While this calculator provides a good estimate, it's important to remember that these are just approximations. Individual metabolic rates can vary, and factors not included in the calculation (like certain medical conditions, medication, or body composition) can influence your actual calorie needs. Always consult with a healthcare professional or a registered dietitian before making significant changes to your diet or exercise routine.

Use this tool as a starting point to understand your body's energy requirements and to guide your nutritional planning effectively.