Macro calculator
Enter your daily calories, get grams of carbs, protein and fat.
How do I calculate my macros?
Multiply your daily calories by each share, then divide by calories per gram: 4 for carbs and protein, 9 for fat. On 2,000 calories, 50% carbs is 1,000 calories — 250 g.
What macro ratio should I use?
For adults, the Dietary Reference Intakes give ranges rather than one ratio: 45–65% of calories from carbohydrate, 10–35% from protein and 20–35% from fat. The presets here stay inside those ranges; the calculator flags a custom split that does not.
How many calories should I eat?
That depends on your age, size and activity — the calorie calculator estimates it. Enter the result here to split it into macros.
Why is fat 9 calories per gram?
Fat holds more energy per gram than carbohydrate or protein. These are the standard Atwater factors used on nutrition labels.
Do the percentages have to add up to 100?
Yes — they are shares of the same total. The calculator warns you if they do not.
How do I turn grams back into percentages?
Multiply the grams by calories per gram and divide by total calories. 140 g of protein is 140 × 4 = 560 calories; on a 2,200-calorie day that is 25.5%.
Why are my grams of fat so low when the share is 30%?
The percentages are shares of calories, and a gram of fat has more than twice the calories of a gram of carbohydrate. A fat share therefore turns into far fewer grams.
How the grams are calculated
Each share is multiplied by the daily calories to get calories per nutrient, then divided by the energy per gram: 4 for carbohydrate and protein and 9 for fat. These are the general Atwater factors; food labels may use more specific values. The ranges the tool checks are the Acceptable Macronutrient Distribution Ranges from the Dietary Reference Intakes: 45 to 65% carbohydrate, 10 to 35% protein and 20 to 35% fat, set for adults as ranges associated with a reduced risk of chronic disease while meeting nutrient needs.
Worked example: 2,200 calories at 50/20/30
Carbohydrate: 50% of 2,200 is 1,100 calories, or 275 g. Protein: 20% is 440 calories, 110 g. Fat: 30% is 660 calories, 73 g. Together 2,200 calories. The fat share is 30% of calories but only 73 g, against 275 g of carbohydrate, for the reason in the question above.
Mistakes to avoid
Reading the percentages as shares of weight is the main one: a 30% fat share is not 30% of the food's grams. The shares must add to 100, otherwise the grams do not match the calorie total you entered. The ranges apply to adults; children have different ones. A preset is a starting point and says nothing about your own health needs, and the calorie total itself should come from an estimate that fits your size and activity.
Sources: Institute of Medicine, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005) for the AMDR; Atwater energy factors for 4-4-9. Related tools: calorie calculator, protein calculator, water intake calculator.
For general information only — not medical advice. Talk with your doctor or another health professional about your own health. How we check our calculators.