Calories from macros are estimated with the FDA's Atwater factors: protein and carbohydrate supply about 4 calories per gram, fat about 9. Enter grams of protein, carbs, and fat below and this calculator multiplies each by its factor and sums them to give total energy and the percentage of calories from each macro, the same arithmetic behind a Nutrition Facts label.

Protein (g) Carbohydrate (g) Fat (g)

How your split compares to common targets

Percent of calories from each macro across common dietary patterns, general guidelines aligned with the USDA Acceptable Macronutrient Distribution Ranges, not personalized advice. The bars use the same protein / carbs / fat color order as your result above.

Balanced (AMDR midpoint) 20% · 50% · 30%

e.g., DIGIORNO Pizza, cheese topping, rising crust, frozen, baked is close to this split

High-protein 35% · 35% · 30%

e.g., Veggie burgers or soyburgers, unprepared is close to this split

Mediterranean 20% · 48% · 32%

e.g., LITTLE CAESARS 14" Original Round Cheese Pizza, Regular Crust is close to this split

Low-carb 30% · 20% · 50%

e.g., KFC, Crispy Chicken Strips is close to this split

Ketogenic 20% · 5% · 75%

e.g., Cheese, pasteurized process, American, fortified with vitamin D is close to this split

Protein Carbs Fat

Source: USDA Dietary Reference Intakes (AMDR) and common dietary-pattern definitions. Ranges are general guidance, consult a doctor or registered dietitian for personalized targets.

How are calories calculated from macros?

According to the U.S. Food and Drug Administration, whose Nutrition Facts label standard governs more than 1,000,000 packaged products in the GetFoodFacts database (April 2026 release), food energy is estimated from the three macronutrients using the Atwater factors: protein and carbohydrate each supply about four calories per gram, while fat supplies about nine. Multiply the grams of each macro by its factor, add the results, and the sum approximates the calories a food provides. The same arithmetic underlies the calorie figure printed on the label, which is why a high-fat food packs more energy into the same weight than a lean, protein-rich one. Alcohol, where present, adds roughly seven calories per gram and is not included here. Our editorial team documents the exact factors and rounding on the methodology page.

The percentage split shows where a food's energy actually comes from, which is often more revealing than the gram amounts alone. A food can look protein-rich by weight yet draw most of its calories from fat, and the bar above makes that visible at a glance. To apply this to real items, look up any food on GetFoodFacts to see its macro breakdown, or open the protein-density rankings to find foods that deliver the most protein per calorie. The example food shown for each dietary pattern above is pulled live from the same April 2026 database.