Calorie Calculator Online

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Scientific Calorie Calculator

Male Female
Sedentary (Office job, little to no exercise) Lightly Active (Light exercise 1-3 days/week) Moderately Active (Moderate exercise 3-5 days/week) Very Active (Hard exercise 6-7 days/week) Extra Active (Very hard exercise, physical job or 2x training)

Your Results

Maintenance
kcal/day
Weight Loss
kcal/day
Weight Gain
kcal/day
function calculateCalories() { var gender = document.getElementById('gender').value; var age = parseFloat(document.getElementById('age').value); var weight = parseFloat(document.getElementById('weight').value); var height = parseFloat(document.getElementById('height').value); var activity = parseFloat(document.getElementById('activity').value); if (isNaN(age) || isNaN(weight) || isNaN(height)) { alert("Please enter valid numbers for age, weight, and height."); return; } var bmr; if (gender === 'male') { bmr = (10 * weight) + (6.25 * height) – (5 * age) + 5; } else { bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161; } var tdee = bmr * activity; var maintenance = Math.round(tdee); var loss = Math.round(tdee – 500); var gain = Math.round(tdee + 500); document.getElementById('maintenance-val').innerHTML = maintenance; document.getElementById('loss-val').innerHTML = loss; document.getElementById('gain-val').innerHTML = gain; document.getElementById('results-area').style.display = 'block'; }

Understanding the Calorie Calculator Online

A calorie calculator is an essential tool for anyone looking to manage their body weight, whether the goal is fat loss, muscle gain, or maintenance. By using the scientifically-backed Mifflin-St Jeor Equation, this tool estimates your Basal Metabolic Rate (BMR) and your Total Daily Energy Expenditure (TDEE).

How the Calculation Works

Your body requires a specific amount of energy to perform basic life-sustaining functions such as breathing, circulation, and cell production. This is known as your BMR. The calculator factors in your biological sex, age, weight, and height because each of these variables influences metabolic speed. For instance, muscle tissue burns more calories than fat tissue, and metabolic rate typically slows down with age.

The Role of Activity Levels

BMR only accounts for your body at rest. To find your maintenance calories, we apply an activity multiplier:

  • Sedentary: 1.2x (Minimal movement)
  • Lightly Active: 1.375x (Walking or light exercise)
  • Moderately Active: 1.55x (Consistent gym training)
  • Very/Extra Active: 1.725x – 1.9x (Athletes or physical labor)

Realistic Example

Consider a 35-year-old male who weighs 85kg, stands 180cm tall, and works a desk job but exercises 3 times a week (Moderately Active).

  1. His BMR would be approximately 1,800 calories.
  2. Multiplied by 1.55 for his activity, his maintenance calories (TDEE) would be roughly 2,790 calories per day.
  3. To lose weight at a healthy pace (0.5kg per week), he would target a 500-calorie deficit, aiming for 2,290 calories.

Tips for Accuracy

While an online calorie calculator provides a highly accurate starting point, it is an estimate. To refine your numbers, track your caloric intake and your body weight over 2-3 weeks. If your weight stays the same, you have found your true maintenance level. Always consult with a nutritionist or healthcare provider before making significant changes to your diet, especially if you have underlying health conditions.

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