What does a macro calculator do?

It splits a daily calorie target into grams of carbs, protein, and fat using a percentage split that you choose, so you know what to aim for in a food-tracking app.

Why do my macros not add up to my calorie target exactly?

Macros are rounded to whole grams for readability. The underlying calculation uses 4 kcal/g for carbs and protein and 9 kcal/g for fat (Atwater factors), so a rounded gram total may be ±1–3% of your input.

Which preset should I pick?

Balanced 40/30/30 fits most people. Low-carb and Keto suit those targeting steady blood-sugar control. High-protein is popular for strength training and cutting phases. Custom is for any plan a coach or dietitian has prescribed.

Why does the Keto preset use only 5% carbs?

A ketogenic diet typically requires carbs at 5–10% of calories to keep most people in nutritional ketosis. The 5% setting is the lower end commonly used in published keto protocols.

Does this tool save my inputs?

No. Calories and percentages are processed in your browser only and are cleared when you close the tab.

Is the macro calculator free?

Yes — completely free, no signup or limits.

Macro Calculator

Split daily calories into carb, protein, and fat grams with preset or custom ratios.

Written by Golam Rabbani, Founder & Lead Engineer — Last updated 2026-05-01

This interactive tool requires JavaScript. Read the formula and worked example below; you can compute the result by hand.

How to use this macro calculator

Enter your total daily calorie target (use a TDEE calculator first if you don't know it).
Pick a preset — Balanced, Low-carb, Keto, or High-protein — or choose Custom %.
If Custom is selected, enter carbs/protein/fat percentages that sum to exactly 100%.
Press Calculate to see grams per macro per day plus the calorie breakdown.

About this macro calculator

The macro calculator converts a daily calorie target into grams of carbohydrate, protein, and fat using the user's chosen split. It applies the standard Atwater energy factors (4 kcal/g for carbs and protein, 9 kcal/g for fat) so totals always reconcile back to your input calories. Built-in presets cover Balanced 40/30/30 (carb/protein/fat), Low-carb 25/35/40, Keto 5/30/65, and High-protein 30/40/30; the custom mode lets you set any combination that adds to 100%.

The percentage ranges are informed by the U.S. Dietary Guidelines for Americans and the Institute of Medicine's Acceptable Macronutrient Distribution Ranges (carbs 45–65%, protein 10–35%, fat 20–35%). This is an estimate for informational purposes and is not a substitute for advice from a registered dietitian or qualified clinician.

For example, on a 2,200 kcal/day Balanced (40/30/30) plan: carbs = 2,200 × 0.40 / 4 = 220 g, protein = 2,200 × 0.30 / 4 = 165 g, fat = 2,200 × 0.30 / 9 ≈ 73 g. The tool is useful for setting daily targets to track in apps, planning meals around training goals, and comparing how a Balanced vs Keto split changes your grams at the same calorie intake.

FAQ

What does a macro calculator do?: It splits a daily calorie target into grams of carbs, protein, and fat using a percentage split that you choose, so you know what to aim for in a food-tracking app.
Why do my macros not add up to my calorie target exactly?: Macros are rounded to whole grams for readability. The underlying calculation uses 4 kcal/g for carbs and protein and 9 kcal/g for fat (Atwater factors), so a rounded gram total may be ±1–3% of your input.
Which preset should I pick?: Balanced 40/30/30 fits most people. Low-carb and Keto suit those targeting steady blood-sugar control. High-protein is popular for strength training and cutting phases. Custom is for any plan a coach or dietitian has prescribed.
Why does the Keto preset use only 5% carbs?: A ketogenic diet typically requires carbs at 5–10% of calories to keep most people in nutritional ketosis. The 5% setting is the lower end commonly used in published keto protocols.
Does this tool save my inputs?: No. Calories and percentages are processed in your browser only and are cleared when you close the tab.
Is the macro calculator free?: Yes — completely free, no signup or limits.