Calculate your estimated daily calorie needs for weight maintenance, loss, or gain.
Male
Female
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/sports & physical job or 2x training)
Calculating your daily calorie needs is a fundamental step towards managing your weight and achieving your health goals. Whether you aim to lose, gain, or maintain your current weight, understanding how many calories your body requires is crucial. This calculator uses the Mifflin-St Jeor equation, a widely accepted formula for estimating Basal Metabolic Rate (BMR), and then adjusts it based on your activity level and weight goal.
How the Calculation Works
The process involves two main steps:
Basal Metabolic Rate (BMR): This is the number of calories your body burns at rest to maintain basic life-sustaining functions like breathing, circulation, and cell production. We use the Mifflin-St Jeor equation:
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
Total Daily Energy Expenditure (TDEE): This is your BMR multiplied by an activity factor that accounts for your physical activity level.
TDEE = BMR × Activity Factor
Adjusting for Weight Goals
The calculated TDEE represents the calories needed to maintain your current weight. To lose or gain weight, you need to create a calorie deficit or surplus, respectively. A common guideline is to adjust by approximately 500 calories per day to achieve a weight change of about 0.5 kg (1 lb) per week.
To Lose Weight: Subtract 500 calories from your TDEE.
To Gain Weight: Add 500 calories to your TDEE.
Note: These are estimates. Individual metabolisms can vary, and it's always recommended to consult with a healthcare professional or a registered dietitian for personalized advice.
Factors Influencing Calorie Needs
Several factors contribute to your unique calorie requirements:
Age: Metabolism tends to slow down with age.
Gender: Men typically have higher muscle mass and thus a higher BMR than women.
Weight & Height: Larger body mass requires more calories.
Activity Level: The more active you are, the more calories you burn.
Body Composition: Muscle burns more calories than fat.
Genetics: Individual genetic factors play a role.
Hormonal Factors: Conditions like thyroid issues can significantly impact metabolism.
Using the Calculator
Simply input your age, gender, weight, height, and select your typical activity level and weight goal. The calculator will provide an estimated daily calorie target to help you reach your objectives. Remember this is a starting point; listen to your body and adjust as needed.
function calculateCalories() {
var age = document.getElementById("age").value;
var gender = document.getElementById("gender").value;
var weight = document.getElementById("weight").value;
var height = document.getElementById("height").value;
var activityLevel = document.getElementById("activityLevel").value;
var goal = document.getElementById("goal").value;
var resultDiv = document.getElementById("result");
var errorDiv = document.getElementById("error");
errorDiv.textContent = ""; // Clear previous errors
resultDiv.textContent = ""; // Clear previous results
// Input validation
if (!age || !weight || !height) {
errorDiv.textContent = "Please fill in all required fields (Age, Weight, Height).";
return;
}
var numAge = parseInt(age);
var numWeight = parseFloat(weight);
var numHeight = parseFloat(height);
var numActivityLevel = parseFloat(activityLevel);
if (isNaN(numAge) || numAge <= 0 ||
isNaN(numWeight) || numWeight <= 0 ||
isNaN(numHeight) || numHeight <= 0) {
errorDiv.textContent = "Please enter valid positive numbers for Age, Weight, and Height.";
return;
}
var bmr;
if (gender === "male") {
bmr = (10 * numWeight) + (6.25 * numHeight) – (5 * numAge) + 5;
} else { // female
bmr = (10 * numWeight) + (6.25 * numHeight) – (5 * numAge) – 161;
}
var tdee = bmr * numActivityLevel;
var finalCalories;
if (goal === "maintain") {
finalCalories = tdee;
} else if (goal === "lose") {
finalCalories = tdee – 500;
} else { // gain
finalCalories = tdee + 500;
}
// Ensure calorie count is not unrealistically low for weight loss
if (goal === "lose" && finalCalories < 1200) {
finalCalories = 1200; // Minimum recommended for most adults
errorDiv.textContent = "Note: Calculated calories for weight loss are below 1200. Maintaining at least 1200 is generally recommended.";
}
// Ensure calorie count is not unrealistically low for weight gain (less common issue)
if (goal === "gain" && finalCalories < 1500) {
finalCalories = 1500; // A more reasonable minimum for gaining
errorDiv.textContent += " Note: Calculated calories for weight gain are relatively low. Ensure adequate nutrient intake.";
}
resultDiv.textContent = "Your estimated daily calorie target: " + Math.round(finalCalories) + " calories";
}