Macro Calculator
Percentages are how splits are described and grams are how food is measured. This converts one into the other.
Protein
188g a day
- Protein
- 188 g
- Carbs
- 250 g
- Fat
- 83 g
- Protein calories
- 750
- Carb calories
- 1,000
- Fat calories
- 750
- Protein and carbohydrate carry four calories a gram and fat carries nine, which is why the fat number looks small next to its percentage.
- There is no single correct split. Protein is the one worth getting right — it preserves muscle in a deficit and is the most filling of the three — and the balance between carbohydrate and fat is largely preference.
About the macro calculator
The conversion rests on three numbers that do not change: protein and carbohydrate carry four calories a gram, fat carries nine. That is why a 30% fat allocation produces far fewer grams than a 30% carbohydrate one from the same calorie total — 83 grams against 250 on a 2,500 calorie day.
There is no single correct split, and anyone presenting one as settled is overselling it. What the evidence supports reasonably firmly is that total calories drive weight change and adequate protein preserves muscle while losing it. The division of what is left between carbohydrate and fat is mostly a question of what you can stick to.
Protein is the one worth getting right. It preserves lean tissue in a deficit, it is the most filling of the three by a wide margin, and it costs the most energy to digest. Around 30% of calories is a reasonable default, and working from grams per kilogram of body weight is better still.
A split that does not total 100 is scaled proportionally rather than losing or inventing calories, so you can enter rough figures and still get a sensible answer.
What it works out
- Grams of each macronutrient from a calorie target
- Calories from each, to check the split
- Any percentages, normalised if they do not total 100
The formula
Grams = Calories × Percentage ÷ Calories per gram (4 for protein and carbs, 9 for fat)
Take the share of calories, then divide by what a gram of that macronutrient is worth.
On 2,500 calories at 30% protein: 750 calories, divided by four, is 188 grams. The 40% carbohydrate share is 1,000 calories, divided by four, is 250 grams. The 30% fat share is also 750 calories — but divided by nine it is only 83 grams.
That asymmetry is the whole reason this calculation is worth doing. Protein and fat here have identical calorie allocations and the gram figures differ by more than a factor of two, which is not obvious from the percentages and is what you actually have to eat.
Alcohol, for completeness, is seven calories a gram and is not a macronutrient anyone budgets for deliberately. It displaces the others without contributing anything to them.
- Calories
- The daily target, from maintenance less any deficit.
- Protein
- Four calories a gram. The one worth prioritising.
- Carbohydrate
- Four calories a gram.
- Fat
- Nine calories a gram, which is why its gram figure looks small.
A worked example
A 2,500 calorie day split 30% protein, 40% carbohydrate and 30% fat.
That works out to 188 g a day.
- Protein
- 188 g
- Carbs
- 250 g
- Fat
- 83 g
- Protein calories
- 750
- Carb calories
- 1,000
- Fat calories
- 750
Questions
What is a good macro split?
There is no single right answer. 30/40/30 protein, carbohydrate and fat is a reasonable default. Total calories drive weight change and adequate protein preserves muscle; the rest is largely preference and adherence.
How many calories are in a gram of each?
Protein and carbohydrate are four calories a gram, fat is nine. Alcohol is seven. These are the numbers everything else on this page follows from.
How much protein should I eat?
Somewhere between 1.6 and 2.2 grams per kilogram of body weight if you are training, which for most people is around 25 to 35 per cent of calories. Working from grams per kilogram is more reliable than from a percentage.
Should I eat low carb or low fat?
At matched calories and protein, the two perform very similarly for weight loss. Pick whichever you find easier to sustain — that difference is far larger than any metabolic advantage either has.
Why is the fat number in grams so small?
Because fat carries more than twice the calories per gram. The same 750 calories is 188 grams of protein or 83 grams of fat, which is why a fat percentage always looks larger than the amount of food it represents.
Do my percentages have to add to 100?
No. Anything that does not total 100 is scaled proportionally rather than losing or inventing calories, so rough figures still give a sensible answer.
Do I need to hit these exactly?
No. Protein is worth hitting reasonably closely; the carbohydrate and fat split can move a fair amount day to day without changing anything. Weekly averages matter more than any single day.