Sedentary (little to 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/sports & physical job)
0.25 kg (Gentle)
0.5 kg (Moderate – Recommended)
0.75 kg (Aggressive)
Your Daily Calorie & Macro Targets:
Understanding Macros for Weight Loss
Achieving sustainable weight loss is not just about reducing overall calorie intake; it's also about the composition of those calories. Macronutrients, or "macros," are the three main types of food that the body needs in large amounts: carbohydrates, proteins, and fats. Understanding your ideal macro split can significantly impact your weight loss journey, energy levels, and muscle preservation.
How the Calculator Works:
This calculator estimates your daily macronutrient targets using a multi-step process:
Basal Metabolic Rate (BMR): First, it calculates your BMR using the Mifflin-St Jeor equation, which is considered one of the most accurate formulas for estimating the calories your body burns at rest.
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): Your BMR is then multiplied by an activity factor to estimate your TDEE, the total number of calories you burn per day, including physical activity.
Calorie Deficit for Weight Loss: To lose weight, you need to consume fewer calories than your TDEE. This calculator creates a deficit based on your chosen weekly weight loss goal:
A deficit of 500 calories per day typically results in about 0.5 kg (1 lb) of weight loss per week (since 1 kg of fat is approximately 7700 calories).
The calculator adjusts this deficit based on your goal (0.25kg, 0.5kg, or 0.75kg per week).
Macro Split: Once your target daily calorie intake for weight loss is determined, the calculator divides these calories into macronutrients using a commonly recommended split for weight loss:
Protein: Set at 40% of total calories. Protein is crucial for preserving muscle mass during weight loss, promoting satiety, and has a higher thermic effect than carbs or fats.
Carbohydrates: Set at 30% of total calories. Carbohydrates are the body's primary energy source.
Fats: Set at 30% of total calories. Healthy fats are essential for hormone production and nutrient absorption.
Conversion to Grams: Finally, the percentage of calories for each macro is converted into grams, knowing that:
1 gram of Protein = 4 calories
1 gram of Carbohydrates = 4 calories
1 gram of Fat = 9 calories
Why This Matters for Weight Loss:
A balanced approach to macros can help you feel fuller for longer, maintain energy levels for workouts, and protect lean muscle mass, which is vital for metabolism. Focusing solely on cutting calories without considering macro balance can lead to muscle loss, fatigue, and rebound weight gain. This calculator provides a personalized starting point to guide your nutrition strategy effectively.
Disclaimer: This calculator provides an estimate for educational purposes. Consult with a healthcare professional or registered dietitian for personalized dietary advice.
function calculateMacros() {
var weight = parseFloat(document.getElementById("weight").value);
var height = parseFloat(document.getElementById("height").value);
var age = parseFloat(document.getElementById("age").value);
var gender = document.getElementById("gender").value;
var activityLevel = parseFloat(document.getElementById("activityLevel").value);
var weightLossGoal = parseFloat(document.getElementById("weightLossGoal").value);
var errorMessage = "";
if (isNaN(weight) || weight <= 0) errorMessage += "Please enter a valid weight.\n";
if (isNaN(height) || height <= 0) errorMessage += "Please enter a valid height.\n";
if (isNaN(age) || age <= 0) errorMessage += "Please enter a valid age.\n";
if (errorMessage !== "") {
document.getElementById("macros").innerText = "Error: " + errorMessage;
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 tdee = bmr * activityLevel;
// Calories to burn for weekly goal: 1kg fat ~ 7700 calories
var calorieDeficitPerDay = weightLossGoal * 1000; // Approximately 7700/7 days
var targetCalories = tdee – calorieDeficitPerDay;
// Ensure target calories are not excessively low
if (targetCalories < 1200) {
targetCalories = 1200; // Minimum sensible calorie intake
// Optionally, inform the user if their goal requires too low calories
}
// Macro percentages (example: 40% Protein, 30% Carbs, 30% Fat)
var proteinCalories = targetCalories * 0.40;
var carbCalories = targetCalories * 0.30;
var fatCalories = targetCalories * 0.30;
// Convert calories to grams
var proteinGrams = proteinCalories / 4;
var carbGrams = carbCalories / 4;
var fatGrams = fatCalories / 9;
// Display results
var resultHTML =
"