Estimate your daily calorie and macronutrient needs 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)
0.25 kg (slow and sustainable)
0.5 kg (moderate)
0.75 kg (faster)
1 kg (aggressive, consult a professional)
Your Estimated Daily Nutrition Goals:
Enter your details to see results.
Calories:— kcal
Protein:— g
Carbohydrates:— g
Fat:— g
Understanding Your Weight Loss Nutrition Needs
Losing weight effectively and sustainably involves understanding your body's energy requirements and how to adjust your intake to create a calorie deficit. This calculator helps you estimate your Basal Metabolic Rate (BMR), Total Daily Energy Expenditure (TDEE), and then adjusts those figures for your weight loss goals, along with providing a macronutrient breakdown.
How the Calculator Works:
The calculation is based on established scientific formulas:
Basal Metabolic Rate (BMR): This is the number of calories your body burns at rest to maintain basic functions like breathing, circulation, and cell production. 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 accounts for your BMR plus the calories you burn through physical activity. It's calculated by multiplying your BMR by an activity factor:
TDEE = BMR × Activity Level Factor
Calorie Target for Weight Loss: To lose weight, you need to consume fewer calories than your TDEE. A deficit of 3500 calories generally results in approximately 0.5 kg (1 lb) of fat loss. This calculator creates a deficit based on your chosen weekly weight loss goal:
Target Calories = TDEE – (Weekly Goal (kg) × 7700) / 7
(Since 1 kg of fat is approximately 7700 calories)
Macronutrient Breakdown: Once your target calorie intake is determined, the calculator suggests a balanced distribution of macronutrients, typically:
Protein: Essential for muscle preservation during weight loss. Recommended intake is often 1.6-2.2 grams per kg of body weight.
Fat: Crucial for hormone function and nutrient absorption. Typically set around 20-30% of total calories.
Carbohydrates: Provide energy. The remaining calories after protein and fat are allocated to carbohydrates.
The specific percentages can vary, but this calculator uses a common approach to provide a starting point.
Using the Calculator:
To get the most accurate results, please provide your details:
Current Weight: Your weight in kilograms.
Height: Your height in centimeters.
Age: Your age in years.
Gender: Affects BMR calculations.
Activity Level: Be honest about your daily and weekly physical activity.
Weight Loss Goal: Choose a realistic and healthy rate of weight loss. Faster loss is not always sustainable or healthy.
Disclaimer: This calculator provides estimates for educational purposes. It is not a substitute for professional medical or nutritional advice. Consult with a healthcare provider or registered dietitian before making significant changes to your diet or exercise routine, especially if you have underlying health conditions.
function calculateNutrition() {
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 goal = parseFloat(document.getElementById("goal").value);
// Validate inputs
if (isNaN(weight) || isNaN(height) || isNaN(age) || weight <= 0 || height <= 0 || age <= 0) {
document.getElementById("result-value").innerText = "Please enter valid positive numbers for weight, height, and age.";
document.getElementById("calories").innerText = "–";
document.getElementById("protein").innerText = "–";
document.getElementById("carbs").innerText = "–";
document.getElementById("fat").innerText = "–";
return;
}
// Calculate BMR using Mifflin-St Jeor Equation
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;
}
// Calculate TDEE
var tdee = bmr * activityLevel;
// Calculate target calories for weight loss
// 1 kg fat approx = 7700 calories
// Target deficit per day = (goal kg/week * 7700 kcal/kg) / 7 days/week
var dailyDeficit = (goal * 7700) / 7;
var targetCalories = tdee – dailyDeficit;
// Ensure target calories don't go too low (e.g., below 1200 for women, 1500 for men)
if (gender === "female" && targetCalories < 1200) targetCalories = 1200;
if (gender === "male" && targetCalories < 1500) targetCalories = 1500;
// Macronutrient calculations (example distribution: 40% Carbs, 30% Protein, 30% Fat)
// This is a common starting point, can be adjusted.
var proteinCalories = targetCalories * 0.30;
var fatCalories = targetCalories * 0.30;
var carbCalories = targetCalories * 0.40;
var protein = proteinCalories / 4; // 4 calories per gram of protein
var fat = fatCalories / 9; // 9 calories per gram of fat
var carbs = carbCalories / 4; // 4 calories per gram of carbs
// Alternative macro distribution focusing on higher protein for muscle preservation
// Let's re-calculate macros for a more typical weight loss approach:
// Aim for ~1.6-2.2g protein per kg body weight, ~20-30% fat, rest carbs.
var proteinTargetGrams = Math.max(1.6 * weight, 1.8 * weight); // Example: 1.8g/kg
var proteinGrams = proteinTargetGrams;
var proteinKcal = proteinGrams * 4;
var fatTargetPercent = 0.25; // 25% of calories from fat
var fatKcal = targetCalories * fatTargetPercent;
var fatGrams = fatKcal / 9;
var carbKcal = targetCalories – proteinKcal – fatKcal;
var carbGrams = carbKcal / 4;
// Ensure carbs don't go extremely low if protein/fat are high
if (carbGrams < 100) { // Arbitrary minimum, adjust as needed
carbGrams = 100;
carbKcal = carbGrams * 4;
// Re-allocate remaining calories to fat or protein (simpler to add to fat for now)
fatKcal = targetCalories – proteinKcal – carbKcal;
fatGrams = fatKcal / 9;
if (fatGrams < 0) { // If still negative, adjust protein
fatGrams = 0;
fatKcal = 0;
proteinKcal = targetCalories – carbKcal;
proteinGrams = proteinKcal / 4;
}
}
document.getElementById("calories").innerText = targetCalories.toFixed(0);
document.getElementById("protein").innerText = proteinGrams.toFixed(1);
document.getElementById("carbs").innerText = carbGrams.toFixed(1);
document.getElementById("fat").innerText = fatGrams.toFixed(1);
document.getElementById("result-value").innerHTML = targetCalories.toFixed(0) + " kcal/day"; // Display primary result prominently
}