Macro Calculator
Split your daily calories into protein, carbohydrate and fat based on your goal, with the calorie values per gram and the evidence behind protein targets.
A "65% fat" diet is 45% fat by weight
The percentages above are shares of energy, and food arrives by the gram. Carbohydrate and protein carry about 4 calories a gram and fat carries 9, so the same share of calories buys less than half as much fat by weight. At 2,000 calories:
| Split | By calories | In grams | By weight | Total food |
|---|---|---|---|---|
| balanced | 50/25/25 | 250g / 125g / 56g | 58/29/ 13 | 431 g |
| zone | 40/30/30 | 200g / 150g / 67g | 48/36/ 16 | 417 g |
| low carb | 20/40/40 | 100g / 200g / 89g | 26/51/ 23 | 389 g |
| keto | 10/25/65 | 50g / 125g / 144g | 16/39/ 45 | 319 g |
| high carb | 55/20/25 | 275g / 100g / 56g | 64/23/ 13 | 431 g |
Fat's share of the plate runs a half to two thirds of its share of the calories — a factor of 1.9 on a balanced split, narrowing to 1.4 on keto because by then fat dominates both measures. Anyone told to eat "30% fat" and picturing a third of their plate is picturing roughly twice what the number means.
The total weight moves too, and in the direction people rarely expect. The same 2,000 calories is 431 g of food on a high carb split and 319 g on keto: denser food, less of it on the plate.
And the grams do not add back up
Each figure is rounded to a whole gram on its own, so multiplying them back out does not return the calories you asked for. Across 1,155 combinations of target and split, the mean error is 2.5 calories and the worst is 8.
Fat is the larger part of that, for the same reason it is smaller on the plate: a gram of fat is 9 calories, so rounding it is worth up to 4.5 either way against 2 for the other two. The three together cannot exceed 8.5 calories, which is where the ceiling above comes from.
This is a rounding error of no dietary consequence whatsoever — under half a per cent — and it is worth knowing it is there before wondering why the numbers do not tie out. Pick calories that divide cleanly and it vanishes: 3,600 on a 50/25/25 split gives 450 g, 225 g and 100 g, reconstructing to exactly 3,600.
One more thing the warning does not catch
The message telling you the percentages should total 100 rounds the total before checking it, so anything within half a point passes silently:
| Split | Really totals | Warned? | Calories delivered |
|---|---|---|---|
| 33.3/33.3/33.3 | 99.9% | no | 2,002 of 2,000 |
| 33.4/33.3/33.3 | 100.0% | no | 2,002 of 2,000 |
| 50/25/25.4 | 100.4% | no | 2,004 of 2,000 |
A custom split totalling 100.4% goes through without comment and hands back 2,004 calories. It is four calories, which is to say nothing at all — but if you are wondering why a split you entered carefully comes back slightly off, that is where it went.
How to use
- Enter your daily calorie target.
- Choose a goal, or set your own percentages.
- Read the grams of each macronutrient.
- Adjust based on how you actually feel and perform.
Frequently asked questions
How many calories are in each macronutrient?
Protein and carbohydrate provide about 4 calories per gram, fat about 9, and alcohol about 7. Fat's density is why fat intake moves total calories quickly, and why very low-fat diets can feel voluminous at the same calorie count.
How much protein do I actually need?
The basic requirement to avoid deficiency is modest, but research on body composition consistently supports considerably more for anyone training or in a calorie deficit — commonly cited figures fall around 1.6 to 2.2 grams per kilogram of body weight. Higher intakes have not shown further benefit in most studies.
Does the carbohydrate and fat split matter?
Much less than total calories and protein, for most goals. Studies comparing low-carbohydrate and low-fat diets at matched calories and protein find broadly similar outcomes. The split that matters is the one you can maintain, and which suits your training and preferences.
Why does protein help in a deficit?
It preserves lean tissue when calories are restricted, so more of the weight lost is fat. It is also the most satiating macronutrient per calorie and has the highest thermic effect, meaning more of its energy is spent on digesting it. Those three together are why it gets the emphasis.
Do I need to hit the numbers exactly?
No, and trying to tends to backfire. Getting within a reasonable range consistently matters far more than hitting a precise figure on any given day. Food labels themselves carry a permitted margin of error, so precision beyond a rough band is illusory.
Is fibre counted separately?
It is a carbohydrate but is only partly digestible, so it contributes fewer calories than the label suggests. Some systems subtract fibre to give net carbohydrate. Whichever convention you use, adequate fibre matters for digestive health independently of the macro split, and nothing here is dietary advice.
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