Macro Calculator
This free macro calculator splits a daily calorie target into protein, carbohydrate, and fat grams, using a published percentage split for your chosen diet style. Nothing you enter is sent anywhere or stored.
How to Use It
- Enter your daily calorie target.
- Choose a diet style.
- Your protein, carb, and fat grams update instantly, no submit button.
How It Works
Each diet style is a published percentage split of total daily calories across protein, carbohydrates, and fat. Once your calorie target is divided into calories for each macro, those calories are converted to grams using each macro's standard energy density: protein and carbohydrates both provide about 4 calories per gram, while fat provides about 9, more than double.
Formulas
macro calories = daily calories × (macro % ÷ 100)
protein grams = protein calories ÷ 4
carb grams = carb calories ÷ 4
fat grams = fat calories ÷ 9
A worked example: a 2,000 calorie target on a Balanced split (30% protein, 40% carbs, 30% fat) gives 600 calories of protein (150g), 800 calories of carbs (200g), and 600 calories of fat (66.7g). The same 2,000 calories on a Keto split (25% protein, 5% carbs, 70% fat) instead gives 500 calories of protein (125g), 100 calories of carbs (25g), and 1,400 calories of fat (155.6g), a very different gram breakdown from the identical total calorie count.
These are general population percentage splits, not personalized nutrition advice. Everything runs client-side in your browser. Nothing you enter is sent anywhere or stored.
Frequently Asked Questions
What is a "macro"?
Macro is short for macronutrient: protein, carbohydrates, and fat, the three nutrients that provide calories (unlike micronutrients like vitamins and minerals, which don't). "Tracking macros" means paying attention to how many grams of each you eat, not just total calories.
Why do protein and carbs use 4 calories per gram, but fat uses 9?
These are the standard energy densities used in nutrition science: a gram of protein or carbohydrate provides about 4 calories when metabolized, while a gram of fat provides about 9, more than double. That's why a food high in fat can be much more calorie-dense than one high in protein or carbs, even at the same weight.
How do I choose a diet style if I'm not sure?
Balanced (30% protein, 40% carbs, 30% fat) is a reasonable general-health default that fits most people without a specific goal. The other options suit more specific situations: Low Carb and Keto for reduced carbohydrate intake, High Protein for muscle building or recovery, and Low Fat for reduced fat intake. If you have a specific health goal, a registered dietitian can recommend a split tailored to you.
How is this different from the Calorie Calculator?
The Calorie Calculator estimates how many total calories you need per day, based on your height, weight, age, gender, and activity level. This tool starts from a calorie target you already have, whether from the Calorie Calculator or anywhere else, and splits it into protein, carb, and fat grams instead.
Are these percentage splits based on my personal health data?
No. Each diet style is a published, general-population percentage split, not calculated from anything about you specifically. Two people with very different bodies and goals who enter the same calorie target and diet style will get the identical gram breakdown, since the split itself does not adjust for individual factors.