Calculate your daily calorie target for sustainable weight loss.
Male
Female
Sedentary (Office job, no exercise)
Lightly Active (1-2 days/week)
Moderately Active (3-5 days/week)
Very Active (6-7 days/week)
Extra Active (Physical job + training)
0.25 kg per week
0.5 kg per week
0.75 kg per week
1.0 kg per week
How Your Calorie Deficit is Calculated
The Calorie Deficit Calculator uses the Mifflin-St Jeor Equation, widely considered the most accurate formula for estimating Basal Metabolic Rate (BMR). To determine your specific needs, we follow three primary steps:
Basal Metabolic Rate (BMR): This is the energy your body burns at rest to maintain vital functions like breathing and heart rate.
Total Daily Energy Expenditure (TDEE): We multiply your BMR by an activity factor to account for daily movement and structured exercise.
The Deficit: To lose body fat, you must consume fewer calories than your TDEE. Scientifically, 1kg of body fat is roughly equivalent to 7,700 calories. Therefore, a 0.5kg weekly loss requires a 3,850 calorie weekly deficit, or 550 calories per day.
Healthy Weight Loss Targets
A safe and sustainable weight loss target is generally 0.5kg to 1kg per week. Attempting a larger deficit can lead to muscle loss, metabolic adaptation, and nutrient deficiencies. If your calculated target falls below 1,200 calories (for women) or 1,500 calories (for men), it is recommended to increase physical activity rather than further decreasing food intake.
Example Calculation
Imagine a 35-year-old male, weighing 90kg and 180cm tall, with a moderate activity level:
BMR: 1,885 Calories
TDEE: 1,885 x 1.55 = 2,922 Calories
Weight Loss Goal: 0.5kg per week (550 cal daily deficit)
Daily Target: 2,372 Calories
Maximizing Your Results
While the calorie deficit is the primary driver of fat loss, protein intake is crucial for maintaining lean muscle mass. Aim for 1.6g to 2.2g of protein per kilogram of body weight while staying within your calculated calorie budget. Tracking your intake with a food scale and logging app will significantly improve the accuracy of your progress.
function calculateDeficit() {
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);
var lossGoal = parseFloat(document.getElementById("lossGoal").value);
var resultDiv = document.getElementById("calc-result");
var tdeeOutput = document.getElementById("tdee-output");
var targetOutput = document.getElementById("target-output");
var summaryText = document.getElementById("summary-text");
if (!age || !weight || !height || age <= 0 || weight <= 0 || height <= 0) {
alert("Please enter valid positive 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 dailyDeficit = (lossGoal * 7700) / 7;
var targetCalories = tdee – dailyDeficit;
resultDiv.style.display = "block";
tdeeOutput.innerHTML = "Your Maintenance Calories (TDEE): " + Math.round(tdee).toLocaleString() + " kcal";
targetOutput.innerHTML = "Your Weight Loss Daily Target: " + Math.round(targetCalories).toLocaleString() + " kcal";
var warning = "";
if (targetCalories < 1200 && gender === "female") {
warning = " Note: Your target is below the recommended 1,200 kcal floor for women. Consider a slower loss rate or increasing activity.";
} else if (targetCalories < 1500 && gender === "male") {
warning = " Note: Your target is below the recommended 1,500 kcal floor for men. Consider a slower loss rate or increasing activity.";
}
summaryText.innerHTML = "To lose " + lossGoal + " kg per week, you need a daily deficit of " + Math.round(dailyDeficit) + " calories." + warning;
resultDiv.scrollIntoView({ behavior: 'smooth' });
}