How macro grams are calculated
Each gram of protein or carbohydrate provides about 4 kcal, and each gram of fat about 9 kcal (the Atwater system). Grams are calories allocated to a macro, divided by its energy value.
- calories — total daily calories
- protein% / carb% / fat% — share of calories from each macro
More detail
Choosing a split
40/40/20 (protein/carb/fat) is a common general-fitness starting point. Higher-protein splits (e.g. 40/30/30) suit fat-loss phases where preserving muscle matters; higher-carb splits suit endurance training. The three percentages should add up to 100%.
Tip. Fat has more than double the calories per gram of protein or carbs, so small changes to the fat percentage move fewer grams than the same change to protein or carbs.
Frequently asked questions
What's a good macro split for fat loss?
A higher-protein split like 40/30/30 (protein/carb/fat) is common during fat loss to help preserve muscle. Enter 2000 calories with 40/30/30 above to see 200g protein, 150g carbs, and 66.7g fat.
Why do my percentages need to add up to 100%?
Each percentage represents a share of your total daily calories. If they don't sum to 100%, the grams are still calculated per the entered percentage, but the three macros together won't line up with your calorie total — a warning appears above when that happens.
Why is fat calculated differently from protein and carbs?
Fat provides about 9 kcal per gram versus 4 kcal per gram for protein and carbs (the Atwater factors), so the same calorie allocation converts to fewer grams of fat than of protein or carbs.
Should I track macros or just calories?
Total calories determine weight change; macro splits shape body composition and how full or energized you feel. Most people benefit from tracking both, especially during muscle-building or fat-loss phases.