Calculate your daily calorie needs to reach your weight loss goals effectively.
Male
Female
Sedentary (little or no exercise)
Lightly active (exercise 1-3 days/week)
Moderately active (exercise 3-5 days/week)
Very active (exercise 6-7 days/week)
Super active (physical job or exercise 2x/day)
Mild Weight Loss (0.25 kg / 0.5 lb per week)
Sustainable Weight Loss (0.5 kg / 1 lb per week)
Aggressive Weight Loss (1 kg / 2 lb per week)
Maintenance Calories (TDEE)
2,000 kcal
The amount needed to maintain your current weight.
Daily Calorie Target
1,500 kcal
Eat this amount daily to reach your goal.
Projected Date to Lose 5kg (11lbs)
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Understanding Your Calorie Deficit
A calorie deficit occurs when you consume fewer calories than your body burns. This is the fundamental principle behind weight loss. When your body doesn't get enough energy from food, it taps into stored fat for fuel, leading to weight reduction.
How This Calculator Works
This calculator uses the Mifflin-St Jeor equation, widely considered by nutrition experts to be the most accurate formula for calculating Basal Metabolic Rate (BMR). Here is the process:
BMR Calculation: We calculate the energy your body needs just to function at rest based on your age, gender, height, and weight.
TDEE Calculation: We multiply your BMR by your activity factor to find your Total Daily Energy Expenditure (TDEE). This is your "maintenance" level.
Deficit Application: We subtract a specific number of calories (usually 500-1000) to create a deficit that aligns with your weekly weight loss goals.
Safe Weight Loss Guidelines
While it might be tempting to slash calories drastically for quick results, this is often unsustainable and unhealthy. Most health organizations recommend a safe weight loss rate of 0.5kg to 1kg (1lb to 2lbs) per week.
Deficit Intensity
Calorie Reduction
Expected Loss/Week
Mild
-250 to -300 kcal
0.25 kg (0.5 lb)
Moderate (Recommended)
-500 kcal
0.5 kg (1 lb)
Aggressive
-1000 kcal
1 kg (2 lbs)
Why Activity Level Matters
Your activity level significantly impacts your TDEE. A construction worker burns far more calories than an office worker of the same size. Be honest with your selection in the calculator to ensure an accurate target. If you underestimate your activity, you may be recommended too few calories, leading to fatigue and muscle loss.
Minimum Calorie Recommendations
It is generally recommended that women should not consume fewer than 1,200 calories per day, and men should not consume fewer than 1,500 calories per day without medical supervision. Consuming below these levels can make it difficult to get sufficient nutrients.
var currentUnit = 'metric';
function toggleUnits(unit) {
currentUnit = unit;
var metricDiv = document.getElementById('metric-inputs');
var imperialDiv = document.getElementById('imperial-inputs');
if (unit === 'metric') {
metricDiv.style.display = 'grid';
imperialDiv.style.display = 'none';
} else {
metricDiv.style.display = 'none';
imperialDiv.style.display = 'grid';
}
}
function calculateDeficit() {
// Inputs
var gender = document.getElementById('cd-gender').value;
var age = parseFloat(document.getElementById('cd-age').value);
var activity = parseFloat(document.getElementById('cd-activity').value);
var goalRate = parseFloat(document.getElementById('cd-goal').value); // kg per week
var weightKg = 0;
var heightCm = 0;
// Unit Conversion Logic
if (currentUnit === 'metric') {
weightKg = parseFloat(document.getElementById('cd-weight-kg').value);
heightCm = parseFloat(document.getElementById('cd-height-cm').value);
} else {
var weightLbs = parseFloat(document.getElementById('cd-weight-lbs').value);
var heightFt = parseFloat(document.getElementById('cd-height-ft').value);
var heightIn = parseFloat(document.getElementById('cd-height-in').value);
// Validation for imperial
if (isNaN(weightLbs) || isNaN(heightFt) || isNaN(heightIn)) {
alert("Please enter valid weight and height values.");
return;
}
weightKg = weightLbs * 0.453592;
heightCm = (heightFt * 30.48) + (heightIn * 2.54);
}
// General Validation
if (isNaN(age) || isNaN(weightKg) || isNaN(heightCm) || age < 1 || weightKg < 1 || heightCm < 1) {
alert("Please enter valid numbers for age, weight, and height.");
return;
}
// BMR Calculation (Mifflin-St Jeor)
var bmr = 0;
if (gender === 'male') {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5;
} else {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161;
}
// TDEE Calculation
var tdee = bmr * activity;
// Deficit Calculation
// 1kg fat approx 7700 calories.
// Goal rate is kg/week. e.g. 0.5kg/week = 3850 cal deficit/week = 550/day.
var dailyDeficit = (goalRate * 7700) / 7;
var targetCalories = tdee – dailyDeficit;
// Safety Floor
var safetyWarning = "";
var minCalories = (gender === 'male') ? 1500 : 1200;
if (targetCalories 0) {
daysToLose5kg = Math.ceil((5 * 7700) / actualDailyDeficit);
var targetDate = new Date();
targetDate.setDate(targetDate.getDate() + daysToLose5kg);
dateString = targetDate.toLocaleDateString(undefined, { weekday: 'long', year: 'numeric', month: 'long', day: 'numeric' });
} else {
dateString = "You are at or above maintenance.";
}
// Display Results
document.getElementById('cd-results').style.display = 'block';
document.getElementById('res-tdee').innerHTML = Math.round(tdee).toLocaleString() + ' kcal';
document.getElementById('res-target').innerHTML = Math.round(targetCalories).toLocaleString() + ' kcal' + '' + safetyWarning + '';
document.getElementById('res-date').innerHTML = dateString;
}