How to Calculate Your Calorie Deficit for Weight Loss
Calorie Deficit Calculator
Calculate your daily calorie deficit needed to achieve your weight loss goals. Understanding your calorie needs is fundamental to sustainable weight management.
Your current body weight in kilograms.
Your desired body weight in kilograms.
0.25 kg (approx. 0.5 lbs)
0.5 kg (approx. 1 lb)
0.75 kg (approx. 1.5 lbs)
1 kg (approx. 2 lbs)
A safe and sustainable rate for weight loss is typically 0.5-1 kg per week.
Your BMR is the number of calories your body burns at rest. You can estimate this using online calculators (e.g., Harris-Benedict, Mifflin-St Jeor).
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/week)
Extra Active (very hard exercise/sports & physical job)
Choose the option that best describes your daily physical activity.
Your Weight Loss Calculations
— kcal/day
Total Daily Energy Expenditure (TDEE): — kcal/day
Total Weight to Lose: — kg
Estimated Time to Target: — weeks
Key Assumptions:
1 kg of body fat is approximately 7700 kcal.
Weight loss rate is consistent.
BMR and activity factor remain constant.
Understanding the Calorie Deficit Formula
To calculate your calorie deficit for weight loss, we first determine your Total Daily Energy Expenditure (TDEE), which is the total number of calories your body burns in a day, including your Basal Metabolic Rate (BMR) and the calories burned through physical activity. TDEE is calculated by multiplying your BMR by an activity factor:
TDEE = BMR × Activity Factor
Next, we calculate the total amount of weight you aim to lose in kilograms. A common guideline is that 1 kilogram of body fat is equivalent to approximately 7700 kilocalories (kcal). Therefore, to lose a certain amount of weight, you need to create a total calorie deficit equal to that weight multiplied by 7700 kcal.
Total Calorie Deficit Needed = Total Weight to Lose (kg) × 7700 kcal/kg
Finally, to determine your daily calorie deficit, we divide the total calorie deficit needed by the number of days it will take to achieve your goal. The number of days is calculated by dividing the total weight to lose by your desired weekly weight loss rate and then multiplying by 7.
Daily Calorie Deficit = Total Calorie Deficit Needed / (Days to Target)
Days to Target = (Total Weight to Lose (kg) / Desired Weekly Weight Loss (kg/week)) × 7 days/week
In simpler terms, your daily target intake is your TDEE minus your calculated Daily Calorie Deficit.
Visualizing Your Weight Loss Journey
The chart below illustrates how your calorie deficit translates into estimated weight loss over time, based on your inputs.
Estimated weekly weight loss based on your calculated daily calorie deficit.
Weight Loss Progress Table
Monthly projected weight loss based on your current settings.
Practical Examples of Calorie Deficit Calculation
Example 1: Moderate Weight Loss Goal
Sarah is 30 years old, weighs 75 kg, and wants to reach 68 kg. She works a desk job and exercises moderately 3-4 times a week. Her estimated BMR is 1600 kcal/day. She aims for a sustainable weight loss of 0.5 kg per week.
Inputs:
Current Weight: 75 kg
Target Weight: 68 kg
Desired Weekly Loss: 0.5 kg
BMR: 1600 kcal/day
Activity Level: Moderately Active (Factor: 1.55)
Calculations:
TDEE = 1600 kcal/day × 1.55 = 2480 kcal/day
Total Weight to Lose = 75 kg – 68 kg = 7 kg
Total Calorie Deficit Needed = 7 kg × 7700 kcal/kg = 53900 kcal
Days to Target = (7 kg / 0.5 kg/week) × 7 days/week = 98 days
Interpretation: Sarah needs to consume approximately 1930 calories per day to lose 0.5 kg per week and reach her goal weight in about 14 weeks.
Example 2: Faster Initial Loss
John is 45 years old, weighs 90 kg, and wants to reach 85 kg. He has a physically demanding job and exercises intensely most days. His estimated BMR is 1800 kcal/day. He wants to lose 1 kg per week initially.
Inputs:
Current Weight: 90 kg
Target Weight: 85 kg
Desired Weekly Loss: 1 kg
BMR: 1800 kcal/day
Activity Level: Extra Active (Factor: 1.9)
Calculations:
TDEE = 1800 kcal/day × 1.9 = 3420 kcal/day
Total Weight to Lose = 90 kg – 85 kg = 5 kg
Total Calorie Deficit Needed = 5 kg × 7700 kcal/kg = 38500 kcal
Days to Target = (5 kg / 1 kg/week) × 7 days/week = 35 days
Interpretation: John needs a daily calorie deficit of about 1100 kcal, leading to a target intake of 2320 kcal/day. This allows him to lose 1 kg per week and reach his goal in 5 weeks. Note: Losing 1 kg/week is aggressive and may not be sustainable long-term for everyone.
How to Use This Calorie Deficit Calculator
Enter Current Weight: Input your current body weight in kilograms.
Enter Target Weight: Input your desired body weight in kilograms.
Select Desired Weekly Loss: Choose a realistic weekly weight loss rate. 0.5 kg to 1 kg per week is generally recommended for sustainability and health.
Input BMR: Enter your Basal Metabolic Rate (calories burned at rest). You can estimate this using online BMR calculators if you don't know it.
Select Activity Level: Choose the option that best reflects your typical daily physical activity.
Click 'Calculate': The calculator will immediately show your results.
Reading Your Results:
Primary Result (Daily Calorie Deficit): This is the number of calories you need to consume less than your TDEE each day to achieve your desired weekly weight loss.
TDEE: Your Total Daily Energy Expenditure – the total calories your body burns per day.
Total Weight to Lose: The difference between your current and target weight.
Estimated Time to Target: How many weeks it might take to reach your goal weight at the specified deficit.
Decision-Making Guidance:
Use the calculated daily calorie deficit to inform your eating plan. Aim to consume your TDEE minus the calculated deficit. Remember that this is an estimate; individual results may vary. Adjust your intake or activity level based on your progress and how you feel. Consult a healthcare professional or registered dietitian for personalized advice.
Key Factors Affecting Calorie Deficit Results
While the calorie deficit calculator provides a valuable estimate, several factors can influence actual weight loss outcomes:
Metabolic Adaptation: As you lose weight, your metabolism may slow down slightly. Your BMR and TDEE might decrease, requiring adjustments to maintain the same deficit.
Body Composition Changes: Weight loss isn't just fat. You might lose some muscle mass, which can affect your metabolic rate. Focusing on strength training can help preserve muscle.
Hormonal Fluctuations: Hormones like cortisol, thyroid hormones, and sex hormones can impact appetite, metabolism, and fat storage, influencing weight loss.
Sleep Quality and Stress Levels: Poor sleep and high stress can disrupt hormones that regulate appetite (ghrelin and leptin) and increase cortisol, potentially hindering weight loss efforts.
Nutrient Timing and Food Choices: While total calorie deficit is key, the quality of your calories matters for satiety, energy levels, and overall health. Focusing on nutrient-dense foods can support your goals.
Digestive Health: The efficiency of your digestive system can impact nutrient absorption and overall energy balance, though this is usually a minor factor for most individuals.
Medications and Health Conditions: Certain medications or underlying health conditions (like PCOS or thyroid disorders) can affect metabolism and weight, requiring tailored approaches.
Accuracy of Input Data: The accuracy of your BMR estimation and activity level reporting significantly impacts the calculated TDEE and subsequent deficit.
Frequently Asked Questions (FAQ)
What is a safe daily calorie deficit?
A safe daily calorie deficit is generally considered to be between 500 to 1000 kcal, aiming for a weight loss of 0.5 to 1 kg per week. A deficit larger than this can lead to muscle loss, nutrient deficiencies, and is often unsustainable.
Is it okay to have a calorie deficit of over 1000 kcal per day?
While possible for very rapid initial weight loss, especially for individuals with higher BMIs and TDEEs, a deficit consistently over 1000 kcal per day is generally not recommended for long-term health. It can increase the risk of fatigue, nutrient deficiencies, gallstones, and muscle loss.
How do I calculate my BMR accurately?
You can estimate your BMR using formulas like the Mifflin-St Jeor equation (widely considered more accurate) or the Harris-Benedict equation. Many online calculators use these formulas. For the most accurate measurement, consider a professional metabolic test.
What if my target weight seems unrealistic?
If your target weight is very low or requires an extreme deficit, it might be unrealistic or unhealthy. Focus on sustainable goals, improving body composition (muscle vs. fat), and overall health markers rather than just a number on the scale. Consult a healthcare professional for guidance.
Does exercise increase my TDEE?
Yes, exercise significantly increases your TDEE. The 'Activity Level' factor in the calculator accounts for this. The more intensely and frequently you exercise, the higher your TDEE will be, allowing for a larger calorie deficit without drastically cutting food intake.
How does age affect calorie needs?
As people age, BMR tends to decrease slightly due to loss of muscle mass. This means older individuals may need fewer calories to maintain their weight compared to younger ones with similar body composition, potentially requiring a smaller calorie deficit for weight loss.
Can I calculate a calorie surplus for weight gain?
Yes, you can adapt this concept for weight gain. Instead of a deficit, you'd calculate a surplus. However, the '7700 kcal per kg' rule is more directly applied to fat gain/loss. Muscle gain requires adequate protein and resistance training alongside a moderate surplus.
Is it better to create a deficit through diet or exercise?
A combination is often most effective and sustainable. Diet plays a larger role in creating a significant calorie deficit (it's easier to 'out-eat' exercise). Exercise is crucial for preserving muscle mass, improving cardiovascular health, boosting metabolism, and overall well-being.
Discover practical tips and strategies for adopting a healthier and more sustainable diet.
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var targetWeightInput = document.getElementById('targetWeight');
var weeklyLossRateInput = document.getElementById('weeklyLossRate');
var bmrInput = document.getElementById('bmr');
var activityFactorInput = document.getElementById('activityFactor');
var currentWeightError = document.getElementById('currentWeightError');
var targetWeightError = document.getElementById('targetWeightError');
var bmrError = document.getElementById('bmrError');
var primaryResultDiv = document.getElementById('primaryResult');
var tdeeDiv = document.getElementById('tdee').querySelector('span');
var totalWeightLossKgDiv = document.getElementById('totalWeightLossKg').querySelector('span');
var timeToTargetDiv = document.getElementById('timeToTarget').querySelector('span');
var weightLossChart;
var chartContext;
var progressTableContainer = document.getElementById('progressTableContainer');
function validateInput(inputElement, errorElement, minValue, maxValue) {
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errorElement.textContent = 'Value cannot be greater than ' + maxValue + '.';
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return isValid;
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function updateChart() {
if (!chartContext) {
var canvas = document.getElementById('weightLossChart');
chartContext = canvas.getContext('2d');
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var bmr = parseFloat(bmrInput.value) || 1500;
var activityFactor = parseFloat(activityFactorInput.value) || 1.725;
var currentWeight = parseFloat(currentWeightInput.value) || 70;
var targetWeight = parseFloat(targetWeightInput.value) || 65;
var weeklyLossRate = parseFloat(weeklyLossRateInput.value) || 0.5;
var tdee = bmr * activityFactor;
var totalWeightLossKg = currentWeight – targetWeight;
var daysToTarget = (totalWeightLossKg / weeklyLossRate) * 7;
var dailyCalorieDeficit = (totalWeightLossKg * 7700) / daysToTarget;
var targetDailyIntake = tdee – dailyCalorieDeficit;
if (isNaN(tdee) || isNaN(dailyCalorieDeficit) || isNaN(targetDailyIntake) || tdee <= 0 || dailyCalorieDeficit <= 0 || targetDailyIntake <= 0) {
if (weightLossChart) {
weightLossChart.destroy();
}
return;
}
var weeks = 20; // Chart for next 20 weeks
var labels = [];
var tdeeData = [];
var targetIntakeData = [];
var projectedWeightData = [];
for (var i = 0; i <= weeks; i++) {
labels.push('Week ' + i);
tdeeData.push(tdee);
targetIntakeData.push(targetDailyIntake);
var projectedWeight = currentWeight – (weeklyLossRate * i);
projectedWeightData.push(projectedWeight);
}
if (weightLossChart) {
weightLossChart.destroy();
}
weightLossChart = new Chart(chartContext, {
type: 'line',
data: {
labels: labels,
datasets: [{
label: 'Projected Weight (kg)',
data: projectedWeightData,
borderColor: 'rgba(255, 99, 132, 1)',
backgroundColor: 'rgba(255, 99, 132, 0.2)',
fill: false,
tension: 0.1
}, {
label: 'Target Daily Intake (kcal)',
data: targetIntakeData,
borderColor: 'rgba(54, 162, 235, 1)',
backgroundColor: 'rgba(54, 162, 235, 0.2)',
fill: false,
tension: 0.1
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title: {
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plugins: {
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title: {
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text: 'Weight Loss Projection'
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function updateProgressTable() {
var bmr = parseFloat(bmrInput.value) || 1500;
var activityFactor = parseFloat(activityFactorInput.value) || 1.725;
var currentWeight = parseFloat(currentWeightInput.value) || 70;
var targetWeight = parseFloat(targetWeightInput.value) || 65;
var weeklyLossRate = parseFloat(weeklyLossRateInput.value) || 0.5;
var tdee = bmr * activityFactor;
var totalWeightLossKg = currentWeight – targetWeight;
var daysToTarget = (totalWeightLossKg / weeklyLossRate) * 7;
var dailyCalorieDeficit = (totalWeightLossKg * 7700) / daysToTarget;
var targetDailyIntake = tdee – dailyCalorieDeficit;
if (isNaN(tdee) || isNaN(dailyCalorieDeficit) || isNaN(targetDailyIntake) || tdee <= 0 || dailyCalorieDeficit <= 0 || targetDailyIntake <= 0) {
progressTableContainer.innerHTML = 'Enter valid inputs to see the progress table.';
return;
}
var tableHtml = '
Month
Projected Weight (kg)
Calories to Consume (kcal/day)
';
var months = 6; // Show 6 months
for (var i = 0; i <= months; i++) {
var weeksPassed = i * 4.33; // Approximate weeks in a month
var projectedWeight = currentWeight – (weeklyLossRate * weeksPassed);
if (projectedWeight < targetWeight) projectedWeight = targetWeight; // Don't go below target
tableHtml += '
';
tableHtml += '
Month ' + i + '
';
tableHtml += '
' + projectedWeight.toFixed(1) + '
';
tableHtml += '
' + targetDailyIntake.toFixed(0) + '
';
tableHtml += '
';
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tableHtml += '
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progressTableContainer.innerHTML = tableHtml;
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function calculateCalorieDeficit() {
var isValid = true;
if (!validateInput(currentWeightInput, currentWeightError, 1)) isValid = false;
if (!validateInput(targetWeightInput, targetWeightError, 1)) isValid = false;
if (!validateInput(bmrInput, bmrError, 500)) isValid = false; // BMR typically > 500
if (!isValid) return;
var currentWeight = parseFloat(currentWeightInput.value);
var targetWeight = parseFloat(targetWeightInput.value);
var weeklyLossRate = parseFloat(weeklyLossRateInput.value);
var bmr = parseFloat(bmrInput.value);
var activityFactor = parseFloat(activityFactorInput.value);
var tdee = bmr * activityFactor;
var totalWeightLossKg = currentWeight – targetWeight;
var daysToTarget = (totalWeightLossKg / weeklyLossRate) * 7;
var dailyCalorieDeficit = (totalWeightLossKg * 7700) / daysToTarget;
var targetDailyIntake = tdee – dailyCalorieDeficit;
var timeToTargetWeeks = totalWeightLossKg / weeklyLossRate;
if (isNaN(tdee) || isNaN(dailyCalorieDeficit) || isNaN(targetDailyIntake) || isNaN(timeToTargetWeeks) ||
tdee <= 0 || dailyCalorieDeficit <= 0 || targetDailyIntake <= 0) {
primaryResultDiv.textContent = "Invalid input combination.";
tdeeDiv.textContent = "– kcal/day";
totalWeightLossKgDiv.textContent = "– kg";
timeToTargetDiv.textContent = "– weeks";
} else {
primaryResultDiv.textContent = dailyCalorieDeficit.toFixed(0) + " kcal/day";
tdeeDiv.textContent = tdee.toFixed(0) + " kcal/day";
totalWeightLossKgDiv.textContent = totalWeightLossKg.toFixed(1) + " kg";
timeToTargetDiv.textContent = timeToTargetWeeks.toFixed(1) + " weeks";
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updateChart();
updateProgressTable();
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function resetCalculator() {
currentWeightInput.value = '70';
targetWeightInput.value = '65';
weeklyLossRateInput.value = '0.5';
bmrInput.value = '1500';
activityFactorInput.value = '1.725';
currentWeightError.textContent = '';
targetWeightError.textContent = '';
bmrError.textContent = '';
calculateCalorieDeficit();
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resultsText += "TDEE: " + tdeeDiv.textContent + "\n";
resultsText += "Total Weight to Lose: " + totalWeightLossKgDiv.textContent + "\n";
resultsText += "Estimated Time to Target: " + timeToTargetDiv.textContent + "\n\n";
resultsText += "— Key Assumptions —\n";
resultsText += "1 kg of body fat is approx. 7700 kcal.\n";
resultsText += "Weight loss rate is consistent.\n";
resultsText += "BMR and activity factor remain constant.\n";
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alert("Results copied to clipboard!");
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function toggleFaq(element) {
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// Initial calculation on load
document.addEventListener('DOMContentLoaded', function() {
calculateCalorieDeficit();
var canvas = document.getElementById('weightLossChart');
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