Calculate your personalized daily macronutrient targets (protein, fat, carbohydrates) based on your body metrics, activity level, and fitness goals.
Male
Female
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/week)
Extra Active (very hard exercise/physical job)
Understanding Precision Nutrition and Macronutrients
Precision nutrition involves tailoring your dietary intake to your unique body, activity level, and specific fitness goals. Instead of generic diet plans, it focuses on calculating the optimal balance of macronutrients – protein, fats, and carbohydrates – to achieve desired outcomes like weight loss, muscle gain, or performance enhancement.
What are Macronutrients?
Protein: Essential for building and repairing tissues, producing enzymes and hormones, and supporting immune function. It's crucial for muscle growth and retention, especially during calorie deficits. Each gram of protein provides approximately 4 calories.
Fats: Vital for hormone production, nutrient absorption (fat-soluble vitamins A, D, E, K), cell membrane integrity, and providing a concentrated source of energy. Healthy fats are crucial for overall health. Each gram of fat provides approximately 9 calories.
Carbohydrates: The body's primary source of energy, fueling your brain, muscles, and central nervous system. They are particularly important for high-intensity exercise. Each gram of carbohydrates provides approximately 4 calories.
How This Calculator Works
This calculator uses a multi-step process to determine your personalized macro targets:
Basal Metabolic Rate (BMR): First, it estimates your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation. BMR is the number of 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 to determine your Total Daily Energy Expenditure (TDEE). This is the total number of calories you burn in a day, including exercise and daily activities.
Goal Adjustment: Based on your selected fitness goal (e.g., weight loss, maintenance, muscle gain), your TDEE is adjusted to create a calorie deficit or surplus.
Macronutrient Allocation: Finally, your total target calories are distributed among protein, fats, and carbohydrates based on your specified protein intake per kilogram of body weight and fat as a percentage of total calories. Carbohydrates fill the remaining caloric needs.
Using Your Macro Targets
Once you have your macro targets, you can use them to plan your meals. Track your food intake using a food diary app or by manually weighing and logging your foods. Aim to hit your protein target consistently, stay within your fat range, and adjust carbohydrates as needed to meet your total calorie goal and energy demands.
Remember, these are starting points. Monitor your progress (weight, measurements, energy levels) and adjust your macros as necessary. Consistency and adherence are key to achieving your nutrition goals.
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function calculateMacros() {
// Get input values
var age = parseFloat(document.getElementById("age").value);
var gender = document.getElementById("gender").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 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) || age <= 0 ||
isNaN(weight) || weight <= 0 ||
isNaN(height) || height <= 0 ||
isNaN(proteinPerKg) || proteinPerKg <= 0 ||
isNaN(fatPercentage) || fatPercentage = 100) {
document.getElementById("result").innerHTML = "Please enter valid positive numbers for all fields. Fat percentage must be between 1 and 99.";
return;
}
// Convert weight to kg
var weightKg = (weightUnit === "lbs") ? weight * 0.453592 : weight;
// Convert height to cm
var heightCm = (heightUnit === "inches") ? height * 2.54 : height;
// 1. 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;
}
// 2. Determine Total Daily Energy Expenditure (TDEE) based on activity level
var activityMultiplier;
switch (activityLevel) {
case "sedentary":
activityMultiplier = 1.2;
break;
case "light":
activityMultiplier = 1.375;
break;
case "moderate":
activityMultiplier = 1.55;
break;
case "very":
activityMultiplier = 1.725;
break;
case "extra":
activityMultiplier = 1.9;
break;
default:
activityMultiplier = 1.2; // Default to sedentary
}
var tdee = bmr * activityMultiplier;
// 3. Adjust TDEE for Goal to get Target Calories
var targetCalories;
switch (goal) {
case "maintain":
targetCalories = tdee;
break;
case "mildDeficit": // ~15% deficit
targetCalories = tdee * 0.85;
break;
case "moderateDeficit": // ~25% deficit
targetCalories = tdee * 0.75;
break;
case "aggressiveDeficit": // ~35% deficit
targetCalories = tdee * 0.65;
break;
case "mildSurplus": // ~10% surplus
targetCalories = tdee * 1.10;
break;
case "moderateSurplus": // ~15% surplus
targetCalories = tdee * 1.15;
break;
case "aggressiveSurplus": // ~20% surplus
targetCalories = tdee * 1.20;
break;
default:
targetCalories = tdee; // Default to maintain
}
// Ensure targetCalories is not excessively low for health
if (targetCalories < 1200 && goal.includes("Deficit")) { // Minimum for deficit
targetCalories = 1200;
} else if (targetCalories < 1500 && !goal.includes("Deficit")) { // Minimum for maintenance/surplus
targetCalories = 1500;
}
// 4. Macronutrient Allocation
// Protein: Based on g/kg body weight
var proteinGrams = proteinPerKg * weightKg;
var proteinCalories = proteinGrams * 4;
// Fat: Based on percentage of total calories
var fatCalories = targetCalories * (fatPercentage / 100);
var fatGrams = fatCalories / 9;
// Carbohydrates: Remaining calories
var carbCalories = targetCalories – proteinCalories – fatCalories;
var carbGrams = carbCalories / 4;
// Handle cases where carbCalories might be negative due to aggressive protein/fat targets on low-calorie goals
if (carbCalories < 0) {
carbCalories = 0;
carbGrams = 0;
// Optionally, redistribute or warn. For now, just cap at 0.
// This scenario implies protein/fat targets are too high for the calorie goal.
}
// Display results
var resultHtml = "
Your Daily Macronutrient Targets:
";
resultHtml += "Target Calories: " + Math.round(targetCalories) + " kcal";
resultHtml += "Protein: " + Math.round(proteinGrams) + " g (" + Math.round(proteinCalories) + " kcal)";
resultHtml += "Fat: " + Math.round(fatGrams) + " g (" + Math.round(fatCalories) + " kcal)";
resultHtml += "Carbohydrates: " + Math.round(carbGrams) + " g (" + Math.round(carbCalories) + " kcal)";
resultHtml += "These are estimated targets. Individual needs may vary. Consult a healthcare professional or registered dietitian for personalized advice.";
document.getElementById("result").innerHTML = resultHtml;
}