Estimate your daily calorie needs for weight maintenance, gain, or loss.
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)
Your estimated daily calorie needs will appear here.
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 management, muscle gain, or simply maintaining a healthy lifestyle. The most common methods use formulas like the Mifflin-St Jeor equation or the Harris-Benedict equation to estimate your Basal Metabolic Rate (BMR), which is the number of calories your body burns at rest. This BMR is then multiplied by an activity factor to account for your daily physical activity.
The Mifflin-St Jeor Equation
The Mifflin-St Jeor equation is widely considered one of the most accurate formulas for calculating BMR:
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)
Once your BMR is calculated, you multiply it by an activity factor to estimate your Total Daily Energy Expenditure (TDEE) – the total number of calories you burn in a day.
Sedentary: BMR × 1.2
Lightly active: BMR × 1.375
Moderately active: BMR × 1.55
Very active: BMR × 1.725
Extra active: BMR × 1.9
Adjusting for Weight Goals
To lose or gain weight, you need to create a calorie deficit or surplus, respectively. A common guideline is to aim for a surplus or deficit of approximately 500 calories per day to achieve a weight change of about 0.5 kg (1 pound) per week.
Weight Loss: Subtract 500 calories from your TDEE.
Weight Gain: Add 500 calories to your TDEE.
Weight Maintenance: Your TDEE is your target.
How This Calculator Works
This calculator uses the Mifflin-St Jeor equation to calculate your BMR based on your age, gender, weight, and height. It then applies the activity factor corresponding to your chosen activity level to determine your TDEE. Finally, it adjusts this TDEE based on your weight goal (maintain, lose, or gain) to provide your estimated daily calorie target.
Disclaimer: This calculator provides an estimate. Individual metabolic rates can vary. For personalized advice, consult a healthcare professional or a registered dietitian.
function calculateCalories() {
var age = parseFloat(document.getElementById("age").value);
var gender = document.getElementById("gender").value;
var weightKg = parseFloat(document.getElementById("weightKg").value);
var heightCm = parseFloat(document.getElementById("heightCm").value);
var activityLevel = parseFloat(document.getElementById("activityLevel").value);
var goal = document.getElementById("goal").value;
var bmr = 0;
// Validate inputs
if (isNaN(age) || age <= 0 ||
isNaN(weightKg) || weightKg <= 0 ||
isNaN(heightCm) || heightCm <= 0) {
document.getElementById("result").innerHTML = "Please enter valid positive numbers for age, weight, and height.";
return;
}
// Calculate BMR using Mifflin-St Jeor equation
if (gender === "male") {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5;
} else { // female
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161;
}
// Calculate TDEE
var tdee = bmr * activityLevel;
var targetCalories = tdee;
// Adjust for goal
if (goal === "lose") {
targetCalories = tdee – 500;
} else if (goal === "gain") {
targetCalories = tdee + 500;
}
// Ensure target calories are not unrealistically low for weight loss
if (targetCalories < 1200 && gender === "female") {
targetCalories = 1200;
} else if (targetCalories < 1500 && gender === "male") {
targetCalories = 1500;
}
document.getElementById("result").innerHTML = "Your estimated daily calorie needs: " + Math.round(targetCalories) + " calories";
}