THE NUMORIX GUIDE
How to use the Macro Calculator
Last reviewed September 14, 2026
What this calculator does
The engine first requires proteinPercent + carbsPercent + fatPercent to equal exactly 100.
Formula and method
The engine first requires proteinPercent + carbsPercent + fatPercent to equal exactly 100. It assigns calories * percentage / 100 to each macro, then divides protein and carbohydrate calories by 4 kcal/g and fat calories by 9 kcal/g. Displayed gram values are rounded to whole grams.
Variables and inputs
Enter daily calories in kcal/day and protein, carbohydrate, and fat percentages. The UI blocks calculation unless the numeric sum is exactly 100, while the engine returns zero values and a warning if called with another sum. Negative percentages are not explicitly rejected.
Worked example
For 2,000 kcal with 30% protein, 40% carbs, and 30% fat: protein = 600 / 4 = 150 g; carbs = 800 / 4 = 200 g; fat = 600 / 9 = 66.7 g, displayed as 67 g. The page shows P: 150g | C: 200g | F: 67g.
How to interpret the result
The result is an energy distribution, not an individualized nutrition prescription. The 4 and 9 kcal/g factors are standard planning approximations, and rounded grams can add back to slightly more or less than the displayed calorie total.
Common mistakes to avoid
Enter percentages rather than gram targets, make the sum exactly 100%, and do not confuse daily calories with calories per meal. Keep protein, carbohydrate, and fat labels matched to the correct fields.
Assumptions and limitations
The route does not use body size, age, activity, medical conditions, fiber, sugar alcohols, food quality, or a goal. It uses exact floating-point equality for the 100% check and does not reject negative percentages. Nutrition targets may require individualized clinical or sports-nutrition guidance.