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)
Maintain Weight
Lose Weight
Gain Weight
Your Estimated Daily Calorie Needs:
— kcal
Understanding Your Daily Calorie Needs
The Personalized Daily Calorie Calculator estimates the number of calories your body needs each day to achieve your specific weight goals. This calculation is based on fundamental principles of metabolism and energy balance.
The Science Behind the Calculation
At its core, our calculator uses the Mifflin-St Jeor equation, which is widely considered one of the most accurate formulas for estimating Basal Metabolic Rate (BMR). BMR represents the number of calories your body burns at rest to maintain basic life functions like breathing, circulation, and cell production.
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
Once your BMR is calculated, it's adjusted based on your lifestyle and activity level to determine your Total Daily Energy Expenditure (TDEE). TDEE is the total number of calories you burn in a day, including BMR and calories burned through physical activity and digestion.
TDEE is calculated by multiplying your BMR by an activity factor:
Sedentary: BMR × 1.2
Lightly active: BMR × 1.375
Moderately active: BMR × 1.55
Very active: BMR × 1.725
Extra active: BMR × 1.9
Achieving Your Weight Goals
Your TDEE is the number of calories you need to eat daily to maintain your current weight. To lose or gain weight, you need to create a calorie deficit or surplus, respectively.
To Lose Weight: A common recommendation is to create a deficit of 500 calories per day, leading to approximately 1 pound (0.45 kg) of weight loss per week. The calculator adjusts your TDEE downwards by 500 kcal for weight loss goals.
To Gain Weight: A surplus of 500 calories per day is generally recommended for a healthy weight gain of about 1 pound (0.45 kg) per week. The calculator adjusts your TDEE upwards by 500 kcal for weight gain goals.
Important Note: These are general estimations. Individual metabolic rates can vary. Consulting with a healthcare professional or a registered dietitian is recommended for personalized advice, especially if you have underlying health conditions.
function calculateCalories() {
var age = document.getElementById("age").value;
var gender = document.getElementById("gender").value;
var weightKg = document.getElementById("weightKg").value;
var heightCm = document.getElementById("heightCm").value;
var activityLevel = document.getElementById("activityLevel").value;
var goal = document.getElementById("goal").value;
var calorieResultElement = document.getElementById("calorieResult");
var goalInfoElement = document.getElementById("goalInfo");
// Validate inputs
if (age === "" || weightKg === "" || heightCm === "") {
calorieResultElement.textContent = "Please fill in all required fields.";
calorieResultElement.style.color = "red";
goalInfoElement.textContent = "";
return;
}
var ageNum = parseFloat(age);
var weightKgNum = parseFloat(weightKg);
var heightCmNum = parseFloat(heightCm);
if (isNaN(ageNum) || isNaN(weightKgNum) || isNaN(heightCmNum) || ageNum <= 0 || weightKgNum <= 0 || heightCmNum <= 0) {
calorieResultElement.textContent = "Please enter valid positive numbers for age, weight, and height.";
calorieResultElement.style.color = "red";
goalInfoElement.textContent = "";
return;
}
var bmr;
if (gender === "male") {
bmr = (10 * weightKgNum) + (6.25 * heightCmNum) – (5 * ageNum) + 5;
} else { // female
bmr = (10 * weightKgNum) + (6.25 * heightCmNum) – (5 * ageNum) – 161;
}
var activityMultiplier;
switch (activityLevel) {
case "sedentary":
activityMultiplier = 1.2;
break;
case "light":
activityMultiplier = 1.375;
break;
case "moderate":
activityMultiplier = 1.55;
break;
case "very_active":
activityMultiplier = 1.725;
break;
case "extra_active":
activityMultiplier = 1.9;
break;
default:
activityMultiplier = 1.2; // Default to sedentary if somehow not set
}
var tdee = bmr * activityMultiplier;
var finalCalories;
var goalText = "";
switch (goal) {
case "maintain":
finalCalories = tdee;
goalText = "This is the estimated daily calorie intake to maintain your current weight.";
break;
case "lose":
finalCalories = tdee – 500; // Approximately 1 lb/week loss
goalText = "To lose weight, aim for approximately 500 fewer calories per day than your TDEE. This may lead to about 1 lb (0.45 kg) of weight loss per week.";
break;
case "gain":
finalCalories = tdee + 500; // Approximately 1 lb/week gain
goalText = "To gain weight, aim for approximately 500 more calories per day than your TDEE. This may lead to about 1 lb (0.45 kg) of weight gain per week.";
break;
default:
finalCalories = tdee; // Default to maintain
goalText = "This is the estimated daily calorie intake to maintain your current weight.";
}
// Ensure calories don't go below a safe minimum, especially for weight loss
if (finalCalories < 1200 && gender === "female") {
finalCalories = 1200;
goalText += " Note: Calorie intake has been adjusted to a minimum of 1200 kcal, which is generally considered a safe lower limit for women.";
} else if (finalCalories < 1500 && gender === "male") {
finalCalories = 1500;
goalText += " Note: Calorie intake has been adjusted to a minimum of 1500 kcal, which is generally considered a safe lower limit for men.";
}
calorieResultElement.textContent = Math.round(finalCalories) + " kcal";
calorieResultElement.style.color = "#28a745"; // Success green
goalInfoElement.textContent = goalText;
}