.calorie-deficit-calculator-container {
font-family: 'Arial', sans-serif;
max-width: 700px;
margin: 20px auto;
padding: 25px;
border: 1px solid #e0e0e0;
border-radius: 10px;
background-color: #fdfdfd;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
}
.calorie-deficit-calculator-container h2 {
color: #2c3e50;
text-align: center;
margin-bottom: 25px;
font-size: 26px;
}
.calorie-deficit-calculator-container .input-group {
margin-bottom: 18px;
display: flex;
flex-wrap: wrap;
align-items: center;
gap: 10px;
}
.calorie-deficit-calculator-container .input-group label {
flex: 1 1 120px;
color: #34495e;
font-weight: bold;
font-size: 15px;
}
.calorie-deficit-calculator-container .input-group input[type="number"],
.calorie-deficit-calculator-container .input-group select {
flex: 2 1 180px;
padding: 10px 12px;
border: 1px solid #ccc;
border-radius: 5px;
font-size: 15px;
color: #333;
box-sizing: border-box;
transition: border-color 0.3s;
}
.calorie-deficit-calculator-container .input-group input[type="number"]:focus,
.calorie-deficit-calculator-container .input-group select:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 5px rgba(0, 123, 255, 0.2);
}
.calorie-deficit-calculator-container .radio-group {
display: flex;
gap: 20px;
flex: 2 1 180px;
}
.calorie-deficit-calculator-container .radio-group label {
font-weight: normal;
color: #34495e;
cursor: pointer;
display: flex;
align-items: center;
gap: 5px;
}
.calorie-deficit-calculator-container .radio-group input[type="radio"] {
margin-right: 5px;
transform: scale(1.1);
}
.calorie-deficit-calculator-container .unit-select {
flex: 0 0 auto;
padding: 10px 12px;
border: 1px solid #ccc;
border-radius: 5px;
font-size: 15px;
color: #333;
background-color: #fff;
cursor: pointer;
}
.calorie-deficit-calculator-container button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #28a745;
color: white;
border: none;
border-radius: 5px;
font-size: 18px;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s ease, transform 0.2s ease;
margin-top: 25px;
}
.calorie-deficit-calculator-container button:hover {
background-color: #218838;
transform: translateY(-2px);
}
.calorie-deficit-calculator-container .result-section {
margin-top: 30px;
padding: 20px;
background-color: #e9f7ef;
border: 1px solid #d4edda;
border-radius: 8px;
text-align: center;
}
.calorie-deficit-calculator-container .result-section h3 {
color: #28a745;
margin-bottom: 15px;
font-size: 22px;
}
.calorie-deficit-calculator-container .result-section p {
font-size: 16px;
color: #333;
line-height: 1.6;
margin-bottom: 10px;
}
.calorie-deficit-calculator-container .result-section p strong {
color: #007bff;
font-size: 17px;
}
.calorie-deficit-calculator-container .error-message {
color: #dc3545;
margin-top: 15px;
text-align: center;
font-weight: bold;
}
@media (max-width: 600px) {
.calorie-deficit-calculator-container .input-group {
flex-direction: column;
align-items: stretch;
}
.calorie-deficit-calculator-container .input-group label {
flex: none;
width: 100%;
margin-bottom: 5px;
}
.calorie-deficit-calculator-container .input-group input[type="number"],
.calorie-deficit-calculator-container .input-group select,
.calorie-deficit-calculator-container .radio-group {
flex: none;
width: 100%;
}
.calorie-deficit-calculator-container .radio-group {
justify-content: space-around;
}
}
function calculateCalorieDeficit() {
var age = parseFloat(document.getElementById('age').value);
var gender = document.querySelector('input[name="gender"]:checked').value;
var weight = parseFloat(document.getElementById('weight').value);
var weightUnit = document.getElementById('weightUnit').value;
var height = parseFloat(document.getElementById('height').value);
var heightUnit = document.getElementById('heightUnit').value;
var activityFactor = parseFloat(document.getElementById('activityLevel').value);
var targetWeightLoss = parseFloat(document.getElementById('targetWeightLoss').value);
var targetWeightLossUnit = document.getElementById('targetWeightLossUnit').value;
var errorMessageDiv = document.getElementById('errorMessage');
var resultDiv = document.getElementById('result');
// Input validation
if (isNaN(age) || age <= 0 || isNaN(weight) || weight <= 0 || isNaN(height) || height <= 0 || isNaN(targetWeightLoss) || targetWeightLoss <= 0) {
errorMessageDiv.textContent = "Please enter valid positive numbers for all fields.";
errorMessageDiv.style.display = 'block';
resultDiv.style.display = 'none';
return;
} else {
errorMessageDiv.style.display = 'none';
}
var weightKg, heightCm;
// Convert weight to kg
if (weightUnit === 'lbs') {
weightKg = weight * 0.453592;
} else {
weightKg = weight;
}
// Convert height to cm
if (heightUnit === 'inches') {
heightCm = height * 2.54;
} else {
heightCm = height;
}
var bmr;
// 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;
}
var tdee = bmr * activityFactor;
var dailyDeficit;
// 1 kg fat = ~7700 calories, 1 lb fat = ~3500 calories
if (targetWeightLossUnit === 'lbs') {
dailyDeficit = (targetWeightLoss * 3500) / 7;
} else { // kg
dailyDeficit = (targetWeightLoss * 7700) / 7;
}
var targetDailyCalories = tdee – dailyDeficit;
// Ensure target daily calories don't go too low (e.g., below 1200 for women, 1500 for men)
var minRecommendedCalories = (gender === 'male') ? 1500 : 1200;
if (targetDailyCalories < minRecommendedCalories) {
errorMessageDiv.textContent = "Warning: The calculated daily calorie intake (" + Math.round(targetDailyCalories) + " calories) is very low. It's generally not recommended to go below " + minRecommendedCalories + " calories/day without medical supervision. Consider a smaller weekly weight loss target.";
errorMessageDiv.style.display = 'block';
targetDailyCalories = minRecommendedCalories; // Cap at minimum for display
}
document.getElementById('displayBMR').textContent = Math.round(bmr);
document.getElementById('displayTDEE').textContent = Math.round(tdee);
document.getElementById('displayDailyDeficit').textContent = Math.round(dailyDeficit);
document.getElementById('displayTargetCalories').textContent = Math.round(targetDailyCalories);
resultDiv.style.display = 'block';
}
Calorie Deficit Calculator
kg
lbs
cm
inches
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/physical job/training twice a day)
kg
lbs
Your Calorie Deficit Plan
Your Basal Metabolic Rate (BMR): calories/day
Your Total Daily Energy Expenditure (TDEE): calories/day
To achieve your target weight loss, you need a daily calorie deficit of: calories/day
Your recommended daily calorie intake for weight loss: calories/day
Understanding Your Calorie Deficit for Effective Weight Loss
Achieving sustainable weight loss often boils down to one fundamental principle: creating a calorie deficit. This means consistently consuming fewer calories than your body burns each day. Our Calorie Deficit Calculator is designed to help you determine the ideal daily calorie intake to reach your weight loss goals safely and effectively.
What is a Calorie Deficit?
A calorie deficit occurs when the number of calories you consume from food and drinks is less than the number of calories your body expends through daily activities and metabolic processes. When this happens, your body turns to stored energy (primarily fat) to make up the difference, leading to weight loss.
How the Calculator Works
Our calculator uses a multi-step approach to provide you with personalized recommendations:
-
Basal Metabolic Rate (BMR): This is the number of calories your body needs to perform basic, life-sustaining functions at rest (like breathing, circulation, and cell production). We use the widely accepted Mifflin-St Jeor equation, which considers your age, gender, weight, and height to estimate your BMR.
- Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
-
Total Daily Energy Expenditure (TDEE): Your TDEE is your BMR adjusted for your activity level. It represents the total number of calories your body burns in a day, including exercise and non-exercise activity. We multiply your BMR by an activity factor based on your reported activity level:
- Sedentary: BMR × 1.2 (little or no exercise)
- Lightly Active: BMR × 1.375 (light exercise/sports 1-3 days/week)
- Moderately Active: BMR × 1.55 (moderate exercise/sports 3-5 days/week)
- Very Active: BMR × 1.725 (hard exercise/sports 6-7 days a week)
- Extra Active: BMR × 1.9 (very hard exercise/physical job/training twice a day)
- Target Calorie Deficit: To lose weight, you need to create a deficit. Generally, a deficit of 500 calories per day is recommended to lose about 1 pound (0.45 kg) per week, as 1 pound of fat is roughly equivalent to 3500 calories (or 1 kg of fat is roughly 7700 calories). Our calculator determines the daily deficit needed to achieve your specified weekly weight loss target.
- Target Daily Calorie Intake: Finally, we subtract your calculated daily deficit from your TDEE to give you the recommended daily calorie intake for weight loss.
Realistic Weight Loss Goals
While it might be tempting to aim for rapid weight loss, a healthy and sustainable rate is typically 1-2 pounds (0.5-1 kg) per week. Larger deficits can lead to muscle loss, nutrient deficiencies, and make it harder to stick to your plan long-term. Our calculator helps you set a realistic target.
Important Considerations
- Individual Variation: These calculations are estimates. Metabolism can vary between individuals due to genetics, body composition, and other factors.
- Nutrient Density: Focus on consuming nutrient-dense foods (lean proteins, whole grains, fruits, vegetables) within your calorie target to ensure you're getting essential vitamins and minerals.
- Exercise: While diet is crucial, incorporating regular physical activity can boost your calorie expenditure, improve overall health, and help preserve muscle mass during weight loss.
- Consult a Professional: Always consult with a healthcare provider or a registered dietitian before making significant changes to your diet or exercise routine, especially if you have underlying health conditions.
Example Calculation:
Let's consider a 30-year-old moderately active male, weighing 75 kg (165 lbs), and 175 cm (69 inches) tall, aiming to lose 0.5 kg (1.1 lbs) per week.
- BMR Calculation:
BMR = (10 × 75 kg) + (6.25 × 175 cm) – (5 × 30 years) + 5
BMR = 750 + 1093.75 – 150 + 5 = 1698.75 calories - TDEE Calculation:
Activity Factor (Moderately Active) = 1.55
TDEE = 1698.75 × 1.55 = 2633.06 calories - Daily Calorie Deficit for 0.5 kg/week loss:
0.5 kg × 7700 calories/kg = 3850 calories per week
Daily Deficit = 3850 / 7 = 550 calories/day - Target Daily Calorie Intake:
Target Calories = TDEE – Daily Deficit
Target Calories = 2633.06 – 550 = 2083.06 calories
So, this individual would aim for approximately 2083 calories per day to achieve a healthy weight loss of 0.5 kg per week.