Health
Macro Calculator
Enter your daily calories. This page gives the macro ranges the science supports, in grams — and explains why a single “perfect” split is a preference, not a rule.
How wide the protein range really is, by calorie level
The AMDR protein band runs from 10% to 35% of calories at every level — a threefold span. A single “protein target” picks one point out of that and calls it the answer.
| Daily calories | Protein, lower (10% of calories) | Protein, upper (35%) |
|---|---|---|
| 1500 kcal | 38 | 131 |
| 2000 kcalThe default above. Protein anywhere from 50 to 175 g. | 50 | 175 |
| 2500 kcal | 63 | 219 |
| 3000 kcal | 75 | 263 |
The formula
Worked example
2000 kcal a day
- protein: 10–35% → 200–700 kcal ÷ 4 = 50–175 g
- carbohydrate: 45–65% → 900–1300 kcal ÷ 4 = 225–325 g
- fat: 20–35% → 400–700 kcal ÷ 9 = 44–78 g
- no single split inside these is the one correct one
Where this goes wrong
Chasing one “perfect” macro split
The split marketed as optimal — 40/30/30, high-protein, low-carb, whatever this week’s is — is a preference dressed as science. The evidence gives ranges, and wide ones: at 2000 kcal the AMDR puts protein anywhere from 50 to 175 g, a 125 g spread. Where you sit inside that is a goal, not a health law — more protein helps hold muscle in a calorie deficit, more carbohydrate fuels hard endurance training, and for most purposes total calories matter far more than the ratio. There is one genuine cap inside the ranges: keep saturated fat under 10% of calories and trans fat near zero. Past that, pick a split you can actually stick to, and change it when your goal changes rather than hunting for a number that does not exist.
Questions
- What are the ideal macros?
- There is no single ideal. The Institute of Medicine’s ranges are carbohydrate 45–65% of calories, protein 10–35%, and fat 20–35%, and anywhere inside them is acceptable. Where you land is a matter of goals and what you can sustain, not a rule — a low-carb eater and an endurance athlete both fall within the ranges at opposite ends.
- How much protein do I actually need?
- The AMDR floor is 10% of calories, and most guidance for building or keeping muscle sits toward the upper end of the range rather than the bottom. Protein above the minimum helps hold muscle when you are eating in a deficit, which is the main reason to push it up. The upper AMDR bound is 35% of calories; going far beyond that displaces the carbohydrate and fat the body also needs.
- Why grams instead of percentages?
- Because you eat grams, not percentages. The ranges are shares of your calories, and this page converts them using the standard energy factors — 4 kcal per gram for carbohydrate and protein, 9 for fat. That 9 is why fat’s gram numbers look small: each gram carries more than twice the energy.
- Does the macro split matter for losing weight?
- Far less than total calories. Weight change is driven by the energy balance, and any split within the ranges can lose or gain weight at the same calorie level. What the split changes is how the diet feels and what you keep: protein toward the higher end helps retain muscle and blunt hunger in a deficit. Fix the calories first, then choose a split you can hold to.