Daily Calorie Needs Calculator
Estimate your daily calorie requirements to maintain, lose, or gain weight based on your personal data and activity level.
.calorie-calculator-container {
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: 700px;
margin: 30px auto;
border: 1px solid #eee;
}
.calorie-calculator-container h2 {
color: #333;
text-align: center;
margin-bottom: 20px;
font-size: 28px;
}
.calorie-calculator-container p {
color: #555;
text-align: center;
margin-bottom: 25px;
line-height: 1.6;
}
.calculator-form .form-group {
margin-bottom: 18px;
display: flex;
flex-wrap: wrap;
align-items: center;
justify-content: space-between;
}
.calculator-form label {
flex: 1;
min-width: 120px;
color: #444;
font-weight: 600;
margin-right: 15px;
font-size: 16px;
}
.calculator-form input[type="number"],
.calculator-form select {
flex: 2;
min-width: 150px;
padding: 10px 12px;
border: 1px solid #ccc;
border-radius: 5px;
font-size: 16px;
color: #333;
background-color: #fff;
box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.05);
transition: border-color 0.3s ease;
}
.calculator-form input[type="number"]:focus,
.calculator-form select:focus {
border-color: #007bff;
outline: none;
box-shadow: 0 0 0 3px rgba(0, 123, 255, 0.25);
}
.calculator-form input[type="radio"] {
margin-left: 10px;
margin-right: 5px;
transform: scale(1.2);
}
.calculator-form input[type="radio"] + label {
flex: none;
min-width: unset;
margin-right: 20px;
font-weight: normal;
}
.calculator-form button {
display: block;
width: 100%;
padding: 12px 20px;
background-color: #007bff;
color: white;
border: none;
border-radius: 5px;
font-size: 18px;
font-weight: 700;
cursor: pointer;
margin-top: 25px;
transition: background-color 0.3s ease, transform 0.2s ease;
box-shadow: 0 2px 5px rgba(0, 123, 255, 0.2);
}
.calculator-form button:hover {
background-color: #0056b3;
transform: translateY(-1px);
}
.calculator-form button:active {
transform: translateY(0);
box-shadow: 0 1px 3px rgba(0, 123, 255, 0.3);
}
.result-container {
margin-top: 30px;
padding: 20px;
background-color: #e9f7ef;
border: 1px solid #d4edda;
border-radius: 8px;
text-align: center;
font-size: 20px;
color: #155724;
font-weight: 600;
line-height: 1.5;
box-shadow: 0 2px 8px rgba(0, 0, 0, 0.08);
}
.result-container strong {
color: #0a3622;
font-size: 24px;
}
@media (max-width: 600px) {
.calorie-calculator-container {
padding: 15px;
margin: 20px auto;
}
.calculator-form .form-group {
flex-direction: column;
align-items: flex-start;
}
.calculator-form label {
margin-bottom: 8px;
width: 100%;
}
.calculator-form input[type="number"],
.calculator-form select {
width: 100%;
min-width: unset;
}
.calculator-form input[type="radio"] + label {
margin-right: 10px;
}
.calculator-form button {
font-size: 16px;
padding: 10px 15px;
}
.result-container {
font-size: 18px;
}
.result-container strong {
font-size: 22px;
}
}
function calculateCalories() {
var age = parseFloat(document.getElementById('ageYears').value);
var gender = document.querySelector('input[name="gender"]:checked').value;
var weightValue = parseFloat(document.getElementById('weightValue').value);
var weightUnit = document.getElementById('weightUnit').value;
var heightValue = parseFloat(document.getElementById('heightValue').value);
var heightUnit = document.getElementById('heightUnit').value;
var activityLevel = document.getElementById('activityLevel').value;
var calorieGoal = document.getElementById('calorieGoal').value;
var resultDiv = document.getElementById('result');
// Input validation
if (isNaN(age) || age <= 0 ||
isNaN(weightValue) || weightValue <= 0 ||
isNaN(heightValue) || heightValue <= 0) {
resultDiv.innerHTML = 'Please enter valid positive numbers for all fields.';
return;
}
// Convert weight to kg
var weightKg = weightValue;
if (weightUnit === 'lbs') {
weightKg = weightValue * 0.453592;
}
// Convert height to cm
var heightCm = heightValue;
if (heightUnit === 'inches') {
heightCm = heightValue * 2.54;
}
// Calculate Basal Metabolic Rate (BMR) using Mifflin-St Jeor Equation
var bmr;
if (gender === 'male') {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5;
} else { // female
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161;
}
// Apply Activity Factor to get Total Daily Energy Expenditure (TDEE)
var activityFactor;
switch (activityLevel) {
case 'sedentary':
activityFactor = 1.2;
break;
case 'light':
activityFactor = 1.375;
break;
case 'moderate':
activityFactor = 1.55;
break;
case 'very':
activityFactor = 1.725;
break;
case 'extra':
activityFactor = 1.9;
break;
default:
activityFactor = 1.2; // Default to sedentary
}
var tdee = bmr * activityFactor;
// Adjust TDEE based on goal
var finalCalories = tdee;
var goalDescription = "";
if (calorieGoal === 'lose') {
finalCalories = tdee – 500; // Approximately 0.5 kg (1 lb) weight loss per week
goalDescription = "to lose weight";
} else if (calorieGoal === 'gain') {
finalCalories = tdee + 500; // Approximately 0.5 kg (1 lb) weight gain per week
goalDescription = "to gain weight";
} else {
goalDescription = "to maintain your current weight";
}
// Ensure calories don't go below a reasonable minimum
if (finalCalories < 1000) {
finalCalories = 1000; // A very low minimum to prevent unhealthy recommendations
}
resultDiv.innerHTML = 'Your estimated daily calorie needs ' + goalDescription + ' are approximately:
' + Math.round(finalCalories) + ' Calories';
}
Understanding Your Calorie Needs
Calories are units of energy that your body uses to perform all its functions, from breathing and thinking to exercising and digesting food. The number of calories you need daily depends on several factors, including your age, gender, weight, height, and activity level.
Basal Metabolic Rate (BMR)
Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to maintain basic life-sustaining functions like circulation, respiration, and cell production. It's the minimum energy required to keep your body functioning if you were to do nothing but rest for 24 hours. Our calculator uses the widely accepted Mifflin-St Jeor equation to estimate your BMR:
- For Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
- For Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
Total Daily Energy Expenditure (TDEE)
While BMR accounts for your resting energy needs, your Total Daily Energy Expenditure (TDEE) includes the calories burned through physical activity. To calculate TDEE, your BMR is multiplied by an activity factor:
- 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)
This TDEE is the approximate number of calories you need to consume daily to maintain your current weight.
Weight Management Goals
Once your TDEE is calculated, you can adjust your calorie intake based on your weight goals:
- Maintain Weight: Consume calories equal to your TDEE.
- Lose Weight: To lose approximately 0.5 kg (1 lb) per week, a deficit of 500 calories per day is generally recommended. This means consuming TDEE – 500 calories.
- Gain Weight: To gain approximately 0.5 kg (1 lb) per week, a surplus of 500 calories per day is generally recommended. This means consuming TDEE + 500 calories.
It's important to note that these are estimates. Individual metabolism, body composition, and other factors can influence actual calorie needs. Always consult with a healthcare professional or registered dietitian for personalized advice.
Example Calculation
Let's consider a 30-year-old female who is 165 cm (5'5″) tall and weighs 60 kg (132 lbs), with a moderately active lifestyle, aiming to maintain her weight.
- BMR Calculation (Female):
BMR = (10 × 60 kg) + (6.25 × 165 cm) – (5 × 30 years) – 161
BMR = 600 + 1031.25 – 150 – 161
BMR = 1320.25 calories
- TDEE Calculation (Moderately Active):
TDEE = BMR × 1.55
TDEE = 1320.25 × 1.55
TDEE = 2046.3875 calories
- Goal Adjustment (Maintain Weight):
Since the goal is to maintain weight, the daily calorie intake would be approximately 2046 calories.
If this individual wanted to lose weight, she would aim for approximately 2046 – 500 = 1546 calories per day.