Calculate your daily macronutrient targets for weight loss.
Male
Female
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)
Your Daily Macronutrient Targets:
Understanding Macronutrients for Weight Loss
Achieving sustainable weight loss involves understanding your body's energy needs and adjusting your intake of macronutrients – protein, carbohydrates, and fats. This calculator helps you estimate your daily calorie needs and then break them down into specific macro targets to support your weight loss journey.
How it Works: The Science Behind the Calculation
The calculation involves several steps:
Basal Metabolic Rate (BMR): This is the number of calories your body burns at rest to maintain basic functions. We use the Mifflin-St Jeor equation, which is widely considered one of the most accurate:
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): This is your BMR multiplied by an activity factor that accounts for your daily physical activity. It represents the total calories you burn in a day.
Calorie Deficit for Weight Loss: To lose weight, you need to consume fewer calories than your TDEE. A common and sustainable deficit is around 500 calories per day, which typically results in a loss of about 0.5 kg (1.1 lbs) per week. This calculator allows you to set a specific weekly weight loss goal, and it adjusts the calorie deficit accordingly (1 kg of fat is approximately 7700 calories).
Macronutrient Distribution: Once your target daily calorie intake for weight loss is determined, we allocate macronutrients based on common and effective ratios for weight loss:
Protein: Essential for muscle maintenance and satiety. A common target is 1.6-2.2 grams per kg of body weight. We use a slightly higher end of this for weight loss to maximize muscle preservation and satiety.
Fat: Crucial for hormone production and nutrient absorption. A typical range is 20-30% of total calories.
Carbohydrates: Provide energy. After protein and fat targets are set, the remaining calories are allocated to carbohydrates.
Using the Calculator
To get the most accurate results, please provide your current weight, target weight, height, age, gender, and a realistic assessment of your typical weekly activity level. Choose a sensible weekly weight loss goal; aiming for 0.5 kg to 1 kg per week is generally considered healthy and sustainable.
Important Considerations
This calculator provides an estimation. Individual metabolic rates can vary.
Consult with a healthcare professional or a registered dietitian before making significant changes to your diet or exercise routine, especially if you have underlying health conditions.
Focus on nutrient-dense whole foods to ensure you're meeting your micronutrient needs.
Consistency is key. Adhering to your macro targets regularly will yield the best results.
function calculateMacros() {
var currentWeight = parseFloat(document.getElementById("currentWeight").value);
var targetWeight = parseFloat(document.getElementById("targetWeight").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 weeklyWeightLossGoal = parseFloat(document.getElementById("weightLossGoal").value);
var resultDiv = document.getElementById("result");
var caloriesResult = document.getElementById("calories");
var proteinResult = document.getElementById("protein");
var carbsResult = document.getElementById("carbs");
var fatResult = document.getElementById("fat");
// Clear previous results
caloriesResult.textContent = "";
proteinResult.textContent = "";
carbsResult.textContent = "";
fatResult.textContent = "";
// Input validation
if (isNaN(currentWeight) || currentWeight <= 0 ||
isNaN(targetWeight) || targetWeight <= 0 ||
isNaN(height) || height <= 0 ||
isNaN(age) || age <= 0 ||
isNaN(weeklyWeightLossGoal) || weeklyWeightLossGoal 2) {
alert("Please enter valid positive numbers for all fields. Weekly weight loss goal should be between 0 and 2 kg.");
return;
}
if (targetWeight >= currentWeight) {
alert("Target weight must be less than current weight for weight loss.");
return;
}
// 1. Calculate BMR (Mifflin-St Jeor Equation)
var bmr;
if (gender === "male") {
bmr = (10 * currentWeight) + (6.25 * height) – (5 * age) + 5;
} else { // female
bmr = (10 * currentWeight) + (6.25 * height) – (5 * age) – 161;
}
// 2. Calculate TDEE
var tdee = bmr * activityLevel;
// 3. Calculate Calorie Deficit for Weight Loss
// 1 kg of fat is approx 7700 calories. Weekly deficit = goal_kg * 7700
// Daily deficit = (goal_kg * 7700) / 7
var dailyCalorieDeficit = (weeklyWeightLossGoal * 7700) / 7;
var targetCalories = tdee – dailyCalorieDeficit;
// Ensure target calories are not excessively low
if (targetCalories < 1200) {
targetCalories = 1200;
alert("Your calculated target calories are very low. For safety, we've set it to 1200 kcal. Please consult a professional.");
}
// 4. Calculate Macronutrient Targets
// Protein: ~1.8g/kg of current weight (can be adjusted)
var proteinGrams = currentWeight * 1.8;
var proteinCalories = proteinGrams * 4; // 4 calories per gram of protein
// Fat: ~25% of target calories
var fatCalories = targetCalories * 0.25;
var fatGrams = fatCalories / 9; // 9 calories per gram of fat
// Carbohydrates: Remaining calories
var carbCalories = targetCalories – proteinCalories – fatCalories;
var carbGrams = carbCalories / 4; // 4 calories per gram of carbohydrate
// Display results
caloriesResult.textContent = "Target Daily Calories: " + targetCalories.toFixed(0) + " kcal";
proteinResult.textContent = "Protein: " + proteinGrams.toFixed(1) + "g (" + proteinCalories.toFixed(0) + " kcal)";
fatResult.textContent = "Fat: " + fatGrams.toFixed(1) + "g (" + fatCalories.toFixed(0) + " kcal)";
carbsResult.textContent = "Carbohydrates: " + carbGrams.toFixed(1) + "g (" + carbCalories.toFixed(0) + " kcal)";
resultDiv.style.display = 'block';
}
// Initialize result display to hidden
document.getElementById("result").style.display = 'none';