Free Macro Calculator
Use this calculator to estimate your daily calorie and macronutrient needs (protein, fat, and carbohydrates) based on your personal details and fitness goals. Understanding your macros is a key step towards achieving your health and fitness objectives, whether it's weight loss, muscle gain, or maintenance.
Understanding Your Macronutrients
Macronutrients, or "macros," are the three main categories of nutrients your body needs in large amounts for energy and to perform essential functions: proteins, fats, and carbohydrates. Each plays a unique role in your health and fitness.
1. Protein
- Role: Essential for building and repairing tissues, making enzymes and hormones, and supporting immune function. Crucial for muscle growth and recovery.
- Sources: Meat, poultry, fish, eggs, dairy, legumes, nuts, seeds, tofu.
- Calories per gram: 4 calories.
2. Fats
- Role: Provide concentrated energy, absorb fat-soluble vitamins (A, D, E, K), protect organs, and support cell growth. Essential for hormone production.
- Sources: Avocados, nuts, seeds, olive oil, fatty fish, butter.
- Calories per gram: 9 calories.
3. Carbohydrates
- Role: The body's primary source of energy. Fuel for the brain, muscles, and central nervous system.
- Sources: Grains, fruits, vegetables, legumes, dairy.
- Calories per gram: 4 calories.
How the Calculator Works
This calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate (BMR), which is the number of calories your body burns at rest. This BMR is then multiplied by an activity factor to determine your Total Daily Energy Expenditure (TDEE) – the total calories you burn in a day, including exercise.
Finally, your TDEE is adjusted based on your chosen goal (weight loss, maintenance, or gain) to arrive at your target daily calorie intake. These calories are then distributed into recommended macronutrient ratios (typically 30% protein, 25% fat, 45% carbohydrates, but these can be customized based on individual needs) to give you your daily macro targets in grams.
Interpreting Your Results
The results provide a starting point for your macro tracking journey. Remember that these are estimates, and individual needs can vary based on genetics, body composition, and specific training regimens. It's often beneficial to track your intake and progress for a few weeks and adjust your macros as needed.
- Weight Loss: A calorie deficit is necessary. The calculator provides a deficit based on your desired rate of loss.
- Weight Gain (Muscle): A calorie surplus is needed, along with adequate protein intake and resistance training.
- Maintenance: Consuming calories equal to your TDEE will help maintain your current weight.
Important Considerations
- Consult a Professional: Always consult with a healthcare provider or a registered dietitian before making significant changes to your diet, especially if you have underlying health conditions.
- Nutrient Density: Focus on whole, unprocessed foods to meet your macro targets. Quality of calories matters as much as quantity.
- Hydration: Don't forget to drink plenty of water throughout the day.
- Fiber: Ensure adequate fiber intake, primarily from carbohydrates like fruits, vegetables, and whole grains.
Example Calculation:
Let's say we have a 30-year-old male, 175 cm tall, weighing 70 kg, with a moderately active lifestyle, aiming for moderate weight loss.
- BMR Calculation (Mifflin-St Jeor): (10 * 70) + (6.25 * 175) – (5 * 30) + 5 = 700 + 1093.75 – 150 + 5 = 1648.75 calories.
- TDEE Calculation: BMR * Activity Factor (1.55 for moderately active) = 1648.75 * 1.55 = 2555.56 calories.
- Calorie Goal (Moderate Weight Loss): TDEE – 500 calories = 2555.56 – 500 = 2055.56 calories.
- Macro Distribution (approximate):
- Protein (30%): 2055.56 * 0.30 = 616.67 calories / 4 cal/g = 154.17 grams
- Fat (25%): 2055.56 * 0.25 = 513.89 calories / 9 cal/g = 57.10 grams
- Carbohydrates (45%): 2055.56 * 0.45 = 925.00 calories / 4 cal/g = 231.25 grams
So, this individual would aim for approximately 2056 calories, with 154g Protein, 57g Fat, and 231g Carbohydrates daily.
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function updateHeightInput() {
var heightUnit = document.getElementById('heightUnit').value;
var heightInputContainer = document.getElementById('heightInputContainer');
heightInputContainer.innerHTML = "; // Clear current inputs
if (heightUnit === 'cm') {
heightInputContainer.innerHTML = ' cm';
} else {
heightInputContainer.innerHTML = ' ft in';
}
}
function calculateMacros() {
var gender = document.querySelector('input[name="gender"]:checked').value;
var age = parseFloat(document.getElementById('age').value);
var weight = parseFloat(document.getElementById('weight').value);
var weightUnit = document.getElementById('weightUnit').value;
var heightUnit = document.getElementById('heightUnit').value;
var activityLevel = document.getElementById('activityLevel').value;
var goal = document.getElementById('goal').value;
var resultDiv = document.getElementById('result');
// Input validation
if (isNaN(age) || age <= 0 || isNaN(weight) || weight <= 0) {
resultDiv.innerHTML = 'Please enter valid positive numbers for age and weight.';
return;
}
var heightCm;
if (heightUnit === 'cm') {
heightCm = parseFloat(document.getElementById('heightCm').value);
if (isNaN(heightCm) || heightCm <= 0) {
resultDiv.innerHTML = 'Please enter a valid positive number for height in cm.';
return;
}
} else {
var heightFt = parseFloat(document.getElementById('heightFt').value);
var heightIn = parseFloat(document.getElementById('heightIn').value);
if (isNaN(heightFt) || heightFt < 0 || isNaN(heightIn) || heightIn 11) {
resultDiv.innerHTML = 'Please enter valid numbers for height in feet and inches.';
return;
}
heightCm = (heightFt * 30.48) + (heightIn * 2.54);
}
// Convert weight to kg if in lbs
var weightKg = (weightUnit === 'lbs') ? weight * 0.453592 : weight;
// 1. Calculate BMR (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;
}
// 2. Calculate TDEE (Total Daily Energy Expenditure)
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;
}
var tdee = bmr * activityFactor;
// 3. Adjust TDEE for Goal
var calorieAdjustment;
switch (goal) {
case 'maintain': calorieAdjustment = 0; break;
case 'mildLoss': calorieAdjustment = -250; break; // ~0.25 kg/week
case 'moderateLoss': calorieAdjustment = -500; break; // ~0.5 kg/week
case 'extremeLoss': calorieAdjustment = -1000; break; // ~1 kg/week
case 'mildGain': calorieAdjustment = 250; break;
case 'moderateGain': calorieAdjustment = 500; break;
case 'extremeGain': calorieAdjustment = 1000; break;
default: calorieAdjustment = 0;
}
var targetCalories = tdee + calorieAdjustment;
// Ensure target calories don't go too low for extreme loss
if (targetCalories < 1200 && gender === 'female' && goal.includes('Loss')) {
targetCalories = 1200;
resultDiv.innerHTML = 'Warning: Calculated calories for extreme weight loss are very low. Adjusted to a minimum of 1200 calories for safety. Consult a professional.';
} else if (targetCalories < 1500 && gender === 'male' && goal.includes('Loss')) {
targetCalories = 1500;
resultDiv.innerHTML = 'Warning: Calculated calories for extreme weight loss are very low. Adjusted to a minimum of 1500 calories for safety. Consult a professional.';
}
// 4. Calculate Macronutrients (default ratios: Protein 30%, Fat 25%, Carbs 45%)
var proteinCalories = targetCalories * 0.30;
var fatCalories = targetCalories * 0.25;
var carbCalories = targetCalories * 0.45;
var proteinGrams = proteinCalories / 4; // 4 calories per gram of protein
var fatGrams = fatCalories / 9; // 9 calories per gram of fat
var carbGrams = carbCalories / 4; // 4 calories per gram of carbohydrate
// Display results
var output = '
Your Estimated Daily Macro Needs:
';
output += '
';
output += '- Target Calories: ' + Math.round(targetCalories) + ' kcal
';
output += '- Protein: ' + Math.round(proteinGrams) + ' grams (' + Math.round(proteinCalories) + ' kcal)
';
output += '- Fats: ' + Math.round(fatGrams) + ' grams (' + Math.round(fatCalories) + ' kcal)
';
output += '- Carbohydrates: ' + Math.round(carbGrams) + ' grams (' + Math.round(carbCalories) + ' kcal)
';
output += '
';
output += '
These are general recommendations. Individual needs may vary.';
resultDiv.innerHTML = output;
}
// Initial call to set up height input based on default unit
updateHeightInput();