What each macro does
| Macro | Calories per gram | Main roles |
|---|---|---|
| Protein | 4 | Builds and repairs tissues; helps make enzymes and antibodies. |
| Carbohydrates | 4 | Provide energy. Carb-rich foods can also supply fiber. |
| Fat | 9 | Provides essential fatty acids and helps absorb vitamins A, D, E and K. |
The 4, 4 and 9 figures are useful estimates. Label rounding, fiber and other ingredients can make a food’s printed calories differ slightly from this calculation.
Calories vs. macros
Calories describe how much energy food provides. Macros describe where much of that energy comes from. A calorie target can help with weight planning; looking at protein, carbs and fat can help you choose satisfying meals and support training.
No macro tells the whole story. Fiber, sodium, vitamins, minerals, allergies, cost and the foods you enjoy still matter.
How do you work out your macros?
- Estimate your daily calories for your activity and goal.
- Choose a protein amount that fits your needs.
- Include enough fat, then use carbs for the remaining energy.
The free macro calculator does this arithmetic for you. Its result is a starting estimate, not an exact measurement of your needs.
A simple example
A sample 2,000-calorie day with 125 g protein and 60 g fat leaves about 240 g carbohydrate: 500 protein calories + 540 fat calories + 960 carbohydrate calories = 2,000. This demonstrates the math; it is not a target for everyone.
Do you need to count macros?
No. You can build meals around protein foods, grains or other carbs, fruit or vegetables, and fats without logging every gram. Tracking can be useful when you have a specific question, such as whether your meals contain enough protein.
You do not need to hit every number exactly. Portions, labels and calorie estimates all have uncertainty. Look for a manageable pattern rather than treating small daily differences as mistakes.
Nutrition terms, plainly
Calories (kcal)
A measure of food energy. GetMacros uses kcal when showing calories.
Serving size
The amount the printed nutrient figures describe. A U.S. label serving is not a recommendation for how much to eat.
Portion
The amount you actually eat. It can differ from the label serving.
Total carbohydrate
The carbohydrate total on the source label. Do not add the sugar and fiber lines to that total again.
Added sugars
Sugars in the added-sugars category are already included in total sugars.
Sodium (mg)
The sodium amount, shown in milligrams. A milligram is one thousandth of a gram.
Percent Daily Value (%DV)
A nutrient’s share of its label reference amount per serving. Different nutrients have different references; the column does not add to 100%.
Unknown value
A value the source does not establish exactly. A dash or missing figure is not zero; a published bound such as “less than 1 g” is not an exact amount.
Label terms follow the FDA’s U.S. label guide. Unknown-value handling describes GetMacros. Added October 4, 2026; the earlier article review date is unchanged.