Convert grams of protein, carbs, and fats into total energy intake
Total Estimated Calories:
0 kcal
Caloric Breakdown
● Protein: 0%
● Carbs: 0%
● Fats: 0%
● Alcohol: 0%
How to Calculate Calories from Macros
Understanding the relationship between macronutrients and calories is essential for achieving fitness goals, whether you are looking to lose weight, gain muscle, or maintain your current physique. Calories are not a physical thing but a unit of energy found in the food you consume.
The 4-4-9-7 Rule
Each macronutrient provides a specific amount of energy per gram. Our calculator uses the industry-standard Atwater factors to determine your total caloric intake:
Protein: 4 calories per gram. Essential for muscle repair and hormone production.
Carbohydrates: 4 calories per gram. The body's primary source of quick energy.
Fats: 9 calories per gram. Vital for nutrient absorption and brain health.
Alcohol: 7 calories per gram. Often considered "empty" calories as they provide energy but no nutritional value.
A Practical Example
If you eat a snack that contains 10g of Protein, 20g of Carbohydrates, and 5g of Fat, the math works as follows:
While "calories in vs. calories out" is the fundamental driver of weight change, where those calories come from determines your body composition. High protein intake preserves lean muscle mass during weight loss, while adequate fat intake ensures your hormonal profile remains healthy.
function calculateMacros() {
var p = parseFloat(document.getElementById('macro_protein').value) || 0;
var c = parseFloat(document.getElementById('macro_carbs').value) || 0;
var f = parseFloat(document.getElementById('macro_fats').value) || 0;
var a = parseFloat(document.getElementById('macro_alcohol').value) || 0;
if (p < 0 || c < 0 || f < 0 || a 0) {
var pctP = (calP / totalCal) * 100;
var pctC = (calC / totalCal) * 100;
var pctF = (calF / totalCal) * 100;
var pctA = (calA / totalCal) * 100;
document.getElementById('total_calories_display').innerHTML = Math.round(totalCal).toLocaleString() + " kcal";
document.getElementById('bar_p').style.width = pctP + "%";
document.getElementById('bar_c').style.width = pctC + "%";
document.getElementById('bar_f').style.width = pctF + "%";
document.getElementById('bar_a').style.width = pctA + "%";
document.getElementById('pct_p').innerText = pctP.toFixed(1);
document.getElementById('pct_c').innerText = pctC.toFixed(1);
document.getElementById('pct_f').innerText = pctF.toFixed(1);
document.getElementById('pct_a').innerText = pctA.toFixed(1);
document.getElementById('macro_result_container').style.display = 'block';
// Smooth scroll to result
document.getElementById('macro_result_container').scrollIntoView({ behavior: 'smooth', block: 'nearest' });
} else {
alert("Please enter at least one macro value greater than zero.");
}
}