Macro Calculator — Glossary

Macronutrients (Macros)

The three main nutrients that provide calories: protein, carbohydrates, and fat. “Macro” comes from Greek meaning “large”—these nutrients are needed in larger amounts compared to micronutrients (vitamins and minerals).

Protein

One of three macronutrients. Provides 4 calories per gram according to the Atwater system. Found in foods like meat, fish, eggs, dairy, legumes, and some grains.

Carbohydrates (Carbs)

One of three macronutrients. Provides 4 calories per gram according to the Atwater system. Found in foods like grains, fruits, vegetables, legumes, and sugars.

Fat (Dietary Fat)

One of three macronutrients. Provides 9 calories per gram according to the Atwater system. Found in foods like oils, nuts, seeds, avocados, and animal products.

Atwater System

The standard method for calculating caloric values of macronutrients, developed by Wilbur Atwater in the 1890s. Establishes that protein and carbohydrates provide 4 calories per gram, while fat provides 9 calories per gram. Used by the USDA and FDA for nutrition labeling.

Calorie (kcal)

A unit of energy. In nutrition, “calorie” typically refers to a kilocalorie (kcal). The energy content of food is measured in calories.

Macro Split

The percentage distribution of calories among protein, carbs, and fat. For example, “30/40/30” means 30% of calories from protein, 40% from carbs, and 30% from fat.

IIFYM (If It Fits Your Macros)

A flexible approach to nutrition tracking where individuals aim to meet daily macro gram targets rather than following specific meal plans or food restrictions.

Flexible Dieting

A nutrition tracking approach that focuses on meeting macronutrient targets rather than eliminating specific food groups.

Gram (g)

The unit of measurement for macronutrients. Macro targets are typically expressed in grams per day (e.g., 150g protein).

Daily Value (DV)

Reference amounts of nutrients established by the FDA for nutrition labeling. The Daily Value for protein is 50g based on a 2000-calorie diet.

Percentage (%)

In this calculator, the portion of total calories allocated to each macronutrient. The three percentages must sum to 100%.

Calorie Density

The number of calories per gram of a nutrient. Fat is more calorie-dense (9 cal/g) than protein or carbs (4 cal/g each).

Net Carbs

A calculation sometimes used: total carbohydrates minus fiber. Not used in this calculator, which calculates total carbohydrates.

USDA

United States Department of Agriculture. Establishes the caloric values (Atwater factors) used in this calculator.

FDA

Food and Drug Administration. Uses the Atwater system for nutrition labeling requirements in the United States.

Estimated Values

The results from this calculator are estimates based on the Atwater general factor system. Actual caloric values may vary slightly depending on specific foods consumed.

Rounding

This calculator rounds gram values to whole numbers for practical use. Small discrepancies between input calories and calculated totals may occur due to rounding.