Calculate your daily macronutrient targets for a low-carbohydrate diet.
Male
Female
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 a week)
Extra Active (very hard exercise/sports & physical job or 2x training)
Maintain Weight
Lose Weight
Gain Weight
Typical low-carb diets range from 5-20%.
Protein is crucial for muscle and satiety. Ranges vary widely.
Your Daily Macros:
Based on your inputs
Understanding Low Carb Macros and Their Calculation
A low-carbohydrate diet focuses on reducing carbohydrate intake while increasing fat and protein consumption. This approach can be effective for weight management, improving blood sugar control, and enhancing certain metabolic markers. To follow a low-carb diet effectively, it's essential to understand your macronutrient (macro) targets: carbohydrates, protein, and fat.
Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE)
The foundation of any macro calculation is determining your daily calorie needs. This starts with estimating your Basal Metabolic Rate (BMR) – the number of calories your body burns at rest. We often use the Mifflin-St Jeor equation, which is 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
Next, we calculate your Total Daily Energy Expenditure (TDEE) by multiplying your BMR by an activity factor:
Sedentary: BMR * 1.2
Lightly Active: BMR * 1.375
Moderately Active: BMR * 1.55
Very Active: BMR * 1.725
Extra Active: BMR * 1.9
Finally, we adjust TDEE based on your weight goal:
Maintain Weight: TDEE remains the same.
Lose Weight: Subtract 500 calories from TDEE for approximately 1 lb/week loss.
Gain Weight: Add 500 calories to TDEE for approximately 1 lb/week gain.
Calculating Macronutrient Targets
Once your target daily calories are established, we distribute them among carbohydrates, protein, and fat based on your specified percentages. Remember these calorie values per gram:
Carbohydrates: 4 calories per gram
Protein: 4 calories per gram
Fat: 9 calories per gram
Using your target daily calories and the percentages you entered:
Calories from Carbohydrates = Total Target Calories * (Carbohydrate Percentage / 100)
Carbohydrates (grams) = Calories from Carbohydrates / 4
Calories from Protein = Total Target Calories * (Protein Percentage / 100)
Protein (grams) = Calories from Protein / 4
Calories from Fat = Total Target Calories – Calories from Carbohydrates – Calories from Protein
Fat (grams) = Calories from Fat / 9
Example Calculation:
Let's say a 35-year-old male, 175 cm tall, weighing 70 kg, is moderately active and wants to maintain weight, aiming for 20% carbs and 30% protein.
Therefore, the daily macro targets would be approximately: 2517 Calories, 189g Protein, 140g Fat, 126g Carbohydrates.
Why Use a Low Carb Macro Calculator?
This calculator is a valuable tool for individuals adopting a low-carb lifestyle, whether for:
Weight Loss: By reducing carbohydrates, the body may enter ketosis, burning fat for energy.
Blood Sugar Management: Lowering carb intake can significantly help individuals with diabetes or insulin resistance manage their blood glucose levels.
Increased Satiety: Adequate protein and healthy fats can lead to feeling fuller for longer, reducing overall calorie intake.
Improved Energy Levels: Many report more stable energy throughout the day without the "crashes" associated with high-carb meals.
Remember, these are estimates. Individual needs can vary. It's always recommended to consult with a healthcare professional or a registered dietitian when making significant changes to your diet.
function calculateMacros() {
var age = document.getElementById("age").value;
var gender = document.getElementById("gender").value;
var weightKg = document.getElementById("weightKg").value;
var heightCm = document.getElementById("heightCm").value;
var activityLevel = parseFloat(document.getElementById("activityLevel").value);
var goal = document.getElementById("goal").value;
var carbPercentage = parseFloat(document.getElementById("carbPercentage").value);
var proteinPercentage = parseFloat(document.getElementById("proteinPercentage").value);
var bmr = 0;
var tdee = 0;
var calorieAdjustment = 0;
var targetCalories = 0;
var resultDiv = document.getElementById("result");
var caloriesResult = document.getElementById("caloriesResult");
var proteinResult = document.getElementById("proteinResult");
var fatResult = document.getElementById("fatResult");
var carbsResult = document.getElementById("carbsResult");
// Input validation
if (age <= 0 || weightKg <= 0 || heightCm <= 0 || isNaN(age) || isNaN(weightKg) || isNaN(heightCm) || isNaN(carbPercentage) || isNaN(proteinPercentage)) {
alert("Please enter valid positive numbers for Age, Weight, Height, and percentages.");
return;
}
if (carbPercentage 100 || proteinPercentage 100) {
alert("Carbohydrate and Protein percentages must be between 0 and 100.");
return;
}
if (carbPercentage + proteinPercentage >= 100) {
alert("Carbohydrate and Protein percentages combined should be less than 100% to allow for fat intake.");
return;
}
// Calculate BMR (Mifflin-St Jeor Equation)
if (gender === "male") {
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) + 5;
} else { // female
bmr = (10 * weightKg) + (6.25 * heightCm) – (5 * age) – 161;
}
// Calculate TDEE
tdee = bmr * activityLevel;
// Calculate Target Calories based on goal
if (goal === "lose") {
calorieAdjustment = -500; // Approx 1 lb/week loss
} else if (goal === "gain") {
calorieAdjustment = 500; // Approx 1 lb/week gain
} else { // maintain
calorieAdjustment = 0;
}
targetCalories = tdee + calorieAdjustment;
// Ensure target calories are not negative (especially for weight loss goals with very low TDEE)
if (targetCalories < 1200) { // A minimum reasonable calorie intake
targetCalories = 1200;
if (goal === "lose") {
alert("Target calories set to minimum (1200) due to low TDEE. Weight loss may be slower.");
} else if (goal === "gain") {
alert("Target calories increased to minimum (1200) for healthy gain.");
}
}
// Calculate Macronutrients in grams
var carbCalories = targetCalories * (carbPercentage / 100);
var proteinCalories = targetCalories * (proteinPercentage / 100);
var fatCalories = targetCalories – carbCalories – proteinCalories;
// Ensure fat calories are not negative, redistribute if necessary
if (fatCalories < 0) {
// If fat calories are negative, it means carb + protein percentages are too high.
// Prioritize protein and carbs, and set fat to a minimum reasonable amount,
// or adjust percentages. For simplicity here, we'll alert and set fat to a minimal value.
alert("Carbohydrate and Protein percentages are too high for a balanced intake. Adjusting Fat to minimum.");
fatCalories = targetCalories * 0.10; // Allocate 10% to fat as a minimum
var remainingCalories = targetCalories – fatCalories;
carbCalories = remainingCalories * (carbPercentage / (carbPercentage + proteinPercentage));
proteinCalories = remainingCalories * (proteinPercentage / (carbPercentage + proteinPercentage));
}
var carbsGrams = carbCalories / 4;
var proteinGrams = proteinCalories / 4;
var fatGrams = fatCalories / 9;
// Display results
caloriesResult.innerHTML = "Calories: " + Math.round(targetCalories) + " kcal";
proteinResult.innerHTML = "Protein: " + Math.round(proteinGrams) + "g";
fatResult.innerHTML = "Fat: " + Math.round(fatGrams) + "g";
carbsResult.innerHTML = "Carbohydrates: " + Math.round(carbsGrams) + "g";
resultDiv.style.display = "block";
}