How to Calculate a Calorie

Daily Calorie Needs Calculator

Your Estimated Daily Calorie Needs:

Basal Metabolic Rate (BMR): — calories/day

Total Daily Energy Expenditure (TDEE): — calories/day

Recommended Daily Intake for Goal: — calories/day

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 activityFactor = parseFloat(document.getElementById('activityLevel').value); var weightGoal = document.getElementById('weightGoal').value; var errorDiv = document.getElementById('calorieCalculatorError'); errorDiv.innerHTML = "; // Clear previous errors if (isNaN(age) || age <= 0 || isNaN(weight) || weight <= 0 || isNaN(height) || height <= 0) { errorDiv.innerHTML = 'Please enter valid positive numbers for Age, Weight, and Height.'; document.getElementById('bmrResult').innerHTML = '–'; document.getElementById('tdeeResult').innerHTML = '–'; document.getElementById('calorieGoalResult').innerHTML = '–'; return; } var bmr; // 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 = bmr * activityFactor; var calorieGoal = tdee; // Default to maintain // Adjust TDEE based on weight goal switch (weightGoal) { case 'mildLoss': calorieGoal = tdee – 250; // Approx. 0.25 kg/week loss break; case 'loss': calorieGoal = tdee – 500; // Approx. 0.5 kg/week loss break; case 'extremeLoss': calorieGoal = tdee – 1000; // Approx. 1 kg/week loss break; case 'mildGain': calorieGoal = tdee + 250; // Approx. 0.25 kg/week gain break; case 'gain': calorieGoal = tdee + 500; // Approx. 0.5 kg/week gain break; case 'extremeGain': calorieGoal = tdee + 1000; // Approx. 1 kg/week gain break; case 'maintain': default: calorieGoal = tdee; break; } document.getElementById('bmrResult').innerHTML = Math.round(bmr); document.getElementById('tdeeResult').innerHTML = Math.round(tdee); document.getElementById('calorieGoalResult').innerHTML = Math.round(calorieGoal); }

Understanding Your Daily Calorie Needs

Calculating your daily calorie needs is a fundamental step towards achieving your health and fitness goals, whether it's weight loss, maintenance, or gain. This calculator uses widely accepted formulas to provide an estimate tailored to your individual characteristics and activity level.

What is BMR (Basal Metabolic Rate)?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to perform basic life-sustaining functions. This includes breathing, circulation, cell production, nutrient processing, and maintaining body temperature. It's the minimum amount of energy your body needs to simply exist, without any physical activity.

Our calculator uses the Mifflin-St Jeor equation, which is considered one of the most accurate BMR formulas for the general population:

• 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

What is TDEE (Total Daily Energy Expenditure)?

While BMR accounts for calories burned at rest, your Total Daily Energy Expenditure (TDEE) includes all the calories you burn throughout the day. This encompasses your BMR, plus the energy expended through physical activity, digestion (thermic effect of food), and non-exercise activity thermogenesis (NEAT – like fidgeting or walking around).

To calculate TDEE, your BMR is multiplied by an activity factor:

• 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
• Extremely Active (very hard exercise/physical job/training twice a day): BMR × 1.9

Adjusting for Weight Goals

Once your TDEE is estimated, you can adjust your calorie intake to achieve specific weight goals:

• Maintain Weight: Consume calories equal to your TDEE.
• Weight Loss: To lose weight, you need to create a calorie deficit. A deficit of 500 calories per day typically leads to a loss of about 0.5 kg (1 pound) per week. Our calculator offers options for mild, moderate, and extreme deficits.
• Weight Gain: To gain weight, you need to consume 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. Our calculator offers options for mild, moderate, and extreme surpluses.

Important Considerations

It's crucial to remember that these calculations provide estimates. Individual metabolic rates can vary due to genetics, hormones, body composition, and other factors. For personalized advice and to ensure your diet is healthy and sustainable, always consult with a healthcare professional or a registered dietitian.

This calculator is a helpful tool to get a starting point for understanding your energy needs, but it should not replace professional medical or nutritional guidance.

Example Calculation:

Let's consider a 30-year-old male, weighing 70 kg, standing 175 cm tall, with a moderately active lifestyle, aiming to maintain weight.

1. BMR Calculation (Male):
   BMR = (10 × 70) + (6.25 × 175) – (5 × 30) + 5
   BMR = 700 + 1093.75 – 150 + 5
   BMR = 1648.75 calories/day
2. TDEE Calculation (Moderately Active, factor 1.55):
   TDEE = 1648.75 × 1.55
   TDEE = 2555.56 calories/day
3. Recommended Daily Intake (Maintain Weight):
   Since the goal is to maintain weight, the recommended intake is equal to the TDEE.
   Recommended Intake = 2556 calories/day (rounded)

Using the calculator with these inputs will yield similar results, providing a clear estimate for daily calorie consumption.