Macro Calculator

Your macros — protein, carbohydrate, and fat — are the three nutrients that provide energy. A calorie target tells you how much to eat; your macro split tells you what those calories should be made of. This calculator does both: it estimates your daily calories, then divides them into grams of each macro. Enter your stats in metric or imperial units — it converts automatically.

How your macros are calculated

Here is how to calculate your macros, in two steps:

1. Calories. It estimates your Basal Metabolic Rate with the Mifflin-St Jeor equation, multiplies by an activity factor to get your total daily energy (TDEE), and adjusts for your goal (maintain, lose, or gain).
2. The split. It divides those calories among the three macros using your diet plan’s percentages, then converts each share to grams using the standard energy densities:

Macronutrient	Energy	Grams from calories
Protein	4 kcal/g	kcal ÷ 4
Carbohydrate	4 kcal/g	kcal ÷ 4
Fat	9 kcal/g	kcal ÷ 9

If you’d rather see the calorie step on its own, the calorie calculator and TDEE calculator show exactly where that number comes from.

Diet plans

Each plan is a percentage of total calories from protein / carbs / fat:

Plan	Protein	Carbs	Fat
Balanced	30%	40%	30%
Low-carb	40%	20%	40%
High-protein	40%	35%	25%
Keto	25%	5%	70%

These splits use the Institute of Medicine’s Acceptable Macronutrient Distribution Ranges (45–65% carbs, 20–35% fat, 10–35% protein) as a reference point — the balanced and high-protein plans stay close to them, while low-carb and keto deliberately step further outside. The AMDRs describe intakes associated with a reduced risk of chronic disease while meeting nutrient needs. For the very-low-carb end, the keto calculator scales protein to lean mass instead.

Worked example

A 2,000-calorie day on a balanced 30/40/30 split works out to:

• Protein: 30% of 2,000 = 600 kcal ÷ 4 = 150 g
• Carbs: 40% of 2,000 = 800 kcal ÷ 4 = 200 g
• Fat: 30% of 2,000 = 600 kcal ÷ 9 ≈ 67 g

Macros for weight loss

Losing fat doesn’t need a special macro ratio — it needs a calorie deficit you can stick to. What macros do is protect your results inside that deficit. Set the goal to “lose” so the calorie target drops, then lean on two rules: keep protein high (it preserves muscle and blunts hunger, which is why the high-protein and low-carb plans suit a cut well), and let carbs and fat flex to taste. The calorie calculator sets the deficit; this tool turns it into grams. For the protein side on its own, the protein calculator gives a weight-based target.

Using your numbers

Protein is the macro most worth hitting consistently — it preserves muscle when you’re losing fat and supports muscle growth when you’re gaining, a focus of the International Society of Sports Nutrition’s position stand on diets and body composition. Carbs and fat are more flexible; shift them to suit your appetite, energy, and preferences as long as your calorie total stays roughly on target.