Macronutrient Calculator
Use this calculator to estimate your daily caloric needs and break them down into personalized macronutrient targets (protein, fats, and carbohydrates) based on your body metrics, activity level, and fitness goals.
.macros-inc-calculator-container {
font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
max-width: 700px;
margin: 20px auto;
padding: 25px;
border: 1px solid #e0e0e0;
border-radius: 10px;
background-color: #f9f9f9;
box-shadow: 0 4px 12px rgba(0, 0, 0, 0.08);
color: #333;
}
.macros-inc-calculator-container h2 {
text-align: center;
color: #2c3e50;
margin-bottom: 20px;
font-size: 1.8em;
}
.macros-inc-calculator-container p {
text-align: center;
margin-bottom: 25px;
line-height: 1.6;
color: #555;
}
.calculator-form .form-group {
margin-bottom: 18px;
display: flex;
flex-direction: column;
}
.calculator-form label {
margin-bottom: 8px;
font-weight: bold;
color: #444;
font-size: 0.95em;
}
.calculator-form input[type="number"],
.calculator-form select {
padding: 12px;
border: 1px solid #ccc;
border-radius: 6px;
font-size: 1em;
width: 100%;
box-sizing: border-box;
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 button {
display: block;
width: 100%;
padding: 14px 20px;
background-color: #007bff;
color: white;
border: none;
border-radius: 6px;
font-size: 1.1em;
font-weight: bold;
cursor: pointer;
transition: background-color 0.3s ease, transform 0.2s ease;
margin-top: 25px;
}
.calculator-form button:hover {
background-color: #0056b3;
transform: translateY(-2px);
}
.calculator-form button:active {
transform: translateY(0);
}
.calculator-results {
margin-top: 30px;
padding: 20px;
border: 1px solid #d4edda;
border-radius: 8px;
background-color: #dff0d8;
color: #155724;
font-size: 1.1em;
line-height: 1.8;
display: none; /* Hidden by default */
}
.calculator-results h3 {
color: #28a745;
margin-top: 0;
margin-bottom: 15px;
font-size: 1.5em;
text-align: center;
}
.calculator-results p {
margin-bottom: 10px;
text-align: left;
color: #155724;
}
.calculator-results strong {
color: #000;
}
.calculator-results .macro-item {
display: flex;
justify-content: space-between;
padding: 5px 0;
border-bottom: 1px dashed #c3e6cb;
}
.calculator-results .macro-item:last-child {
border-bottom: none;
}
.calculator-results .total-calories {
font-size: 1.2em;
font-weight: bold;
margin-top: 15px;
padding-top: 10px;
border-top: 2px solid #28a745;
text-align: center;
}
@media (max-width: 600px) {
.macros-inc-calculator-container {
padding: 15px;
}
.calculator-form label,
.calculator-form input,
.calculator-form select,
.calculator-form button {
font-size: 0.9em;
}
.calculator-results {
font-size: 1em;
}
}
function calculateMacros() {
var age = parseFloat(document.getElementById('age').value);
var gender = document.getElementById('gender').value;
var weight = parseFloat(document.getElementById('weight').value); // kg
var height = parseFloat(document.getElementById('height').value); // cm
var activityLevel = document.getElementById('activityLevel').value;
var goal = document.getElementById('goal').value;
var proteinPerKg = parseFloat(document.getElementById('proteinPerKg').value);
var fatPercentage = parseFloat(document.getElementById('fatPercentage').value);
// Input validation
if (isNaN(age) || isNaN(weight) || isNaN(height) || isNaN(proteinPerKg) || isNaN(fatPercentage) ||
age <= 0 || weight <= 0 || height <= 0 || proteinPerKg <= 0 || fatPercentage <= 0) {
document.getElementById('macroResults').innerHTML = 'Please enter valid positive numbers for all fields.';
document.getElementById('macroResults').style.display = 'block';
return;
}
// Step 1: Calculate BMR (Basal Metabolic Rate) using Mifflin-St Jeor Equation
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;
}
// Step 2: Calculate TDEE (Total Daily Energy Expenditure)
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 'extremelyActive':
activityFactor = 1.9;
break;
default:
activityFactor = 1.2; // Default to sedentary
}
var tdee = bmr * activityFactor;
// Step 3: Adjust TDEE for Goal
var adjustedTDEE;
switch (goal) {
case 'maintain':
adjustedTDEE = tdee;
break;
case 'mildDeficit':
adjustedTDEE = tdee – 250; // Approx 0.25 kg/week deficit
break;
case 'moderateDeficit':
adjustedTDEE = tdee – 500; // Approx 0.5 kg/week deficit
break;
case 'aggressiveDeficit':
adjustedTDEE = tdee – 1000; // Approx 1 kg/week deficit
break;
case 'mildSurplus':
adjustedTDEE = tdee + 250; // Approx 0.25 kg/week surplus
break;
case 'moderateSurplus':
adjustedTDEE = tdee + 500; // Approx 0.5 kg/week surplus
break;
default:
adjustedTDEE = tdee; // Default to maintain
}
// Ensure adjustedTDEE doesn't go too low (e.g., below BMR for aggressive deficits)
if (adjustedTDEE < bmr * 0.8) { // Don't go below 80% of BMR
adjustedTDEE = bmr * 0.8;
}
if (adjustedTDEE < 1200 && gender === 'female') { // Minimum for women
adjustedTDEE = 1200;
}
if (adjustedTDEE < 1500 && gender === 'male') { // Minimum for men
adjustedTDEE = 1500;
}
// Step 4: Calculate Macronutrients
var proteinGrams = proteinPerKg * weight;
var proteinCalories = proteinGrams * 4; // 4 calories per gram of protein
var fatCalories = adjustedTDEE * (fatPercentage / 100);
var fatGrams = fatCalories / 9; // 9 calories per gram of fat
var remainingCalories = adjustedTDEE – proteinCalories – fatCalories;
// Adjust fat if protein + fat calories exceed total calories
if (remainingCalories < 0) {
var fatCaloriesToReduce = -remainingCalories;
fatCalories = Math.max(0, fatCalories – fatCaloriesToReduce); // Ensure fat calories don't go negative
fatGrams = fatCalories / 9;
remainingCalories = adjustedTDEE – proteinCalories – fatCalories; // Recalculate remaining
}
var carbGrams = remainingCalories / 4; // 4 calories per gram of carbohydrates
var carbCalories = carbGrams * 4;
// Format results
var totalCaloriesRounded = Math.round(adjustedTDEE);
var proteinGramsRounded = Math.round(proteinGrams);
var proteinCaloriesRounded = Math.round(proteinCalories);
var fatGramsRounded = Math.round(fatGrams);
var fatCaloriesRounded = Math.round(fatCalories);
var carbGramsRounded = Math.round(carbGrams);
var carbCaloriesRounded = Math.round(carbCalories);
var resultsHtml = '
Your Daily Macronutrient Targets
';
resultsHtml += 'Total Daily Calories:
' + totalCaloriesRounded + ' kcal';
resultsHtml += '
Protein:' + proteinGramsRounded + ' g (' + proteinCaloriesRounded + ' kcal)
';
resultsHtml += '
Fats:' + fatGramsRounded + ' g (' + fatCaloriesRounded + ' kcal)
';
resultsHtml += '
Carbohydrates:' + carbGramsRounded + ' g (' + carbCaloriesRounded + ' kcal)
';
document.getElementById('macroResults').innerHTML = resultsHtml;
document.getElementById('macroResults').style.display = 'block';
}
Understanding Macronutrients
Macronutrients, often referred to as "macros," are the three primary nutrients your body needs in large amounts for energy, growth, and repair: proteins, fats, and carbohydrates. Each plays a distinct and vital role in your overall health and fitness.
Protein
Protein is essential for building and repairing tissues, making enzymes and hormones, and supporting immune function. It's crucial for muscle growth and recovery, especially for those engaged in regular physical activity. Sources include meat, fish, eggs, dairy, legumes, and nuts. Each gram of protein provides approximately 4 calories.
Fats
Dietary fats are vital for hormone production, nutrient absorption (especially fat-soluble vitamins A, D, E, K), and providing a concentrated source of energy. Healthy fats are found in avocados, nuts, seeds, olive oil, and fatty fish. While often demonized, adequate fat intake is critical for health. Each gram of fat provides approximately 9 calories.
Carbohydrates
Carbohydrates are your body's primary and most readily available source of energy. They fuel your brain, muscles, and central nervous system. Carbs are found in grains, fruits, vegetables, and legumes. They are particularly important for high-intensity exercise. Each gram of carbohydrate provides approximately 4 calories.
How This Calculator Works
Our Macronutrient Calculator uses a multi-step process to provide personalized recommendations:
- Basal Metabolic Rate (BMR): First, it estimates your BMR using the Mifflin-St Jeor equation, which calculates the calories your body burns at rest to maintain basic bodily functions.
- Total Daily Energy Expenditure (TDEE): Your BMR is then multiplied by an activity factor (based on your selected activity level) to determine your TDEE – the total calories you burn in a day, including exercise and daily activities.
- Goal Adjustment: Your TDEE is adjusted based on your chosen goal (e.g., weight loss, maintenance, or gain). For weight loss, a calorie deficit is created; for weight gain, a surplus is added.
- Macronutrient Split: Finally, the adjusted calorie target is divided into protein, fat, and carbohydrate grams based on your specified preferences. Protein is calculated first based on grams per kilogram of body weight, fat is calculated as a percentage of total calories, and the remaining calories are allocated to carbohydrates.
Interpreting Your Results
The results provide a starting point for your macronutrient intake. It's important to remember that these are estimates. Individual needs can vary based on metabolism, body composition, training intensity, and other factors. Monitor your progress and adjust your macros as needed to align with your body's response and your specific goals. Consistency and adherence are key to achieving results.