Macro Calculator
A macro calculator converts a chosen daily calorie target and a custom protein/carb/fat percentage split into grams per day, using standard energy densities (protein and carbs at 4 kcal/g, fat at 9 kcal/g). The 4/4/9 calories-per-gram figures come from the Atwater system, the same standard used on nutrition labels, which is why converting a percentage split into grams here will match the numbers you would get doing it by hand from any packaged food’s label.
Educational estimate only. Results are not medical, legal, or financial advice. Confirm important decisions with a qualified professional.
How it works
- Enter your daily calorie target.
- Enter your protein, carb, and fat percentage split (must total 100%).
- Read the grams per day for each macronutrient.
Formula grams = (calories × percent / 100) / energy density (4 kcal/g protein & carbs, 9 kcal/g fat)
Frequently asked questions
How is this different from the calorie calculator’s macro breakdown?
The calorie calculator estimates your calorie target and applies a fixed 30/40/30 split. This tool lets you plug in your own calorie target and your own percentage split — useful for a keto, high-protein, or coach-assigned plan.
Why must the percentages total 100?
Because they represent shares of the same calorie budget — percentages that don’t sum to 100 would double-count or leave out calories.
Why is fat 9 kcal/g but protein and carbs are 4?
These are the standard Atwater energy values: fat is more calorie-dense per gram than protein or carbohydrate.
What percentage split should I use?
It depends on your goals and diet approach — this tool computes grams for whatever split you choose, it doesn’t recommend one.
Is this medical or nutrition advice?
No. It is a unit-conversion calculator — consult a registered dietitian for a plan tailored to you.