Use this calculator to estimate your daily calorie needs for fat loss. It calculates your Basal Metabolic Rate (BMR), Total Daily Energy Expenditure (TDEE), and then suggests a calorie target based on your desired weekly weight loss.
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)
0.25 kg (approx. 0.55 lbs)
0.5 kg (approx. 1.1 lbs)
0.75 kg (approx. 1.65 lbs)
1 kg (approx. 2.2 lbs)
function calculateCalories() {
var age = parseFloat(document.getElementById('age').value);
var gender = document.querySelector('input[name="gender"]:checked').value;
var weight = parseFloat(document.getElementById('weight').value);
var height = parseFloat(document.getElementById('height').value);
var activityLevel = document.getElementById('activityLevel').value;
var weightLossGoal = parseFloat(document.getElementById('weightLossGoal').value);
if (isNaN(age) || age <= 0 || isNaN(weight) || weight <= 0 || isNaN(height) || height <= 0) {
document.getElementById('result').innerHTML = '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 { // female
bmr = (10 * weight) + (6.25 * height) – (5 * age) – 161;
}
var activityFactor;
switch (activityLevel) {
case 'sedentary':
activityFactor = 1.2;
break;
case 'lightlyActive':
activityFactor = 1.375;
break;
case 'moderatelyActive':
activityFactor = 1.55;
break;
case 'veryActive':
activityFactor = 1.725;
break;
case 'extraActive':
activityFactor = 1.9;
break;
default:
activityFactor = 1.2; // Default to sedentary if something goes wrong
}
var tdee = bmr * activityFactor;
// 1 kg of fat is approximately 7700 calories
var dailyCalorieDeficit = (weightLossGoal * 7700) / 7;
var targetCalories = tdee – dailyCalorieDeficit;
// Ensure target calories don't go too low for health reasons (e.g., below 1200 for women, 1500 for men)
var minRecommendedCalories = (gender === 'male') ? 1500 : 1200;
if (targetCalories < minRecommendedCalories) {
targetCalories = minRecommendedCalories;
document.getElementById('result').innerHTML =
'Basal Metabolic Rate (BMR): ' + Math.round(bmr) + ' calories/day' +
'Total Daily Energy Expenditure (TDEE): ' + Math.round(tdee) + ' calories/day' +
'Target Daily Calories for Fat Loss: ' + Math.round(targetCalories) + ' calories/day' +
'Note: Your calculated target was below the recommended minimum for healthy fat loss. It has been adjusted to ' + Math.round(targetCalories) + ' calories/day.';
} else {
document.getElementById('result').innerHTML =
'Basal Metabolic Rate (BMR): ' + Math.round(bmr) + ' calories/day' +
'Total Daily Energy Expenditure (TDEE): ' + Math.round(tdee) + ' calories/day' +
'Target Daily Calories for Fat Loss: ' + Math.round(targetCalories) + ' calories/day';
}
}
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font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
background-color: #f9f9f9;
padding: 25px;
border-radius: 10px;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
max-width: 600px;
margin: 20px auto;
border: 1px solid #e0e0e0;
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color: #333;
text-align: center;
margin-bottom: 20px;
font-size: 1.8em;
}
.calculator-container p {
color: #555;
line-height: 1.6;
margin-bottom: 15px;
}
.calc-input-group {
margin-bottom: 15px;
display: flex;
flex-direction: column;
}
.calc-input-group label {
margin-bottom: 8px;
color: #333;
font-weight: bold;
font-size: 0.95em;
}
.calc-input-group input[type="number"],
.calc-input-group select {
padding: 10px 12px;
border: 1px solid #ccc;
border-radius: 5px;
font-size: 1em;
width: 100%;
box-sizing: border-box;
-webkit-appearance: none; /* Remove default browser styling for selects */
-moz-appearance: none;
appearance: none;
background-color: #fff;
}
.calc-input-group input[type="radio"] {
margin-right: 5px;
margin-left: 15px;
}
.calc-input-group input[type="radio"] + label {
font-weight: normal;
display: inline-block;
margin-bottom: 0;
}
.calc-input-group input[type="radio"]:first-of-type + label {
margin-left: 0;
}
button {
background-color: #007bff;
color: white;
padding: 12px 25px;
border: none;
border-radius: 5px;
cursor: pointer;
font-size: 1.1em;
font-weight: bold;
display: block;
width: 100%;
margin-top: 20px;
transition: background-color 0.3s ease;
}
button:hover {
background-color: #0056b3;
}
.calc-result {
margin-top: 25px;
padding: 15px;
background-color: #e9f7ef;
border: 1px solid #d4edda;
border-radius: 8px;
font-size: 1.1em;
color: #155724;
}
.calc-result p {
margin: 8px 0;
color: #155724;
}
.calc-result p strong {
color: #000;
}
Understanding Your Calorie Needs for Fat Loss
Achieving fat loss primarily revolves around creating a calorie deficit, meaning you consume fewer calories than your body burns. This calculator helps you estimate the daily calorie intake required to achieve a specific weight loss goal.
What is BMR (Basal Metabolic Rate)?
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic, life-sustaining functions while at rest. This includes breathing, circulation, cell production, nutrient processing, and organ function. It's the minimum energy required to keep you alive.
What is TDEE (Total Daily Energy Expenditure)?
Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a 24-hour period, including your BMR and the calories burned during physical activity. It accounts for everything from sleeping and eating to exercising and working. Your activity level significantly impacts your TDEE.
How Does Activity Level Affect Calorie Needs?
The more active you are, the more calories your body burns throughout the day. The calculator uses an activity multiplier to adjust your BMR to your TDEE:
Very Active: Hard exercise/sports 6-7 days a week.
Extra Active: Very hard exercise, physical job, or training twice a day.
Setting a Realistic Weight Loss Goal
A healthy and sustainable rate of fat loss is generally considered to be 0.5 kg to 1 kg (1 to 2 pounds) per week. To lose 1 kg of fat, you need to create a deficit of approximately 7700 calories. This means a daily deficit of about 500-1000 calories to achieve a 0.5-1 kg weekly loss.
0.25 kg/week: Requires a daily deficit of approximately 275 calories.
0.5 kg/week: Requires a daily deficit of approximately 550 calories.
0.75 kg/week: Requires a daily deficit of approximately 825 calories.
1 kg/week: Requires a daily deficit of approximately 1100 calories.
Attempting to lose weight too quickly by creating an excessively large calorie deficit can be detrimental to your health, leading to muscle loss, nutrient deficiencies, and a slower metabolism in the long run. The calculator will adjust your target if it falls below generally recommended minimums (e.g., 1200 for women, 1500 for men) to promote healthier practices.
Important Considerations
While this calculator provides a good estimate, individual calorie needs can vary based on genetics, hormones, body composition, and other factors. It's always recommended to:
Consult a healthcare professional or registered dietitian before making significant changes to your diet or exercise routine.
Monitor your progress and adjust your calorie intake as needed.
Focus on nutrient-dense foods to ensure you're getting essential vitamins and minerals even while in a deficit.
Combine diet with regular exercise for optimal fat loss and overall health.