Macro Calculator
Convert daily calories into protein, fat and carbohydrate targets using fixed or custom adult macro splits.
Results
Macro calculator: turn calories into grams
This is a free macro calculator. Enter a daily calorie target, choose how to divide it, and the page returns grams of protein, fat and carbohydrate, the percentage each represents, and the calories each accounts for.
A macros calculator and a macronutrients calculator are the same tool under two names, and this is both. It is a calculator for macros specifically: it does not work out how many calories you should eat, because that depends on your body and activity rather than on any split. The calorie calculator produces that figure, and this page starts where it stops.
Calorie targets from 800 to 8,000 a day are accepted. You can calculate macros online here with no account and nothing stored, and the arithmetic runs entirely in your browser.
How this macro calculator works
The route starts from the daily calorie target you enter, applies the chosen macronutrient percentages, and converts each share into grams using the standard energy factors: protein and carbohydrate at 4 kcal per gram, fat at 9 kcal per gram.
Worked through: at 2,000 kcal on the balanced split, protein is 20 per cent, which is 400 kcal, which divided by 4 is 100 grams. Fat is 30 per cent, which is 600 kcal, which divided by 9 is 67 grams. Carbohydrate is 50 per cent, which is 1,000 kcal, which divided by 4 is 250 grams.
The splits on offer
Three fixed splits and a custom option. None of them is a recommendation; they are common starting points, and the page reports what each produces rather than steering you toward one:
| Split | Ratio | What it does |
|---|---|---|
| Balanced | 20% protein, 30% fat, 50% carbohydrate | A neutral starting point |
| Higher protein | 30% protein, 25% fat, 45% carbohydrate | Protein raised, carbohydrate cut |
| Higher carbohydrate | 20% protein, 25% fat, 55% carbohydrate | Carbohydrate raised |
| Custom | Any three percentages that total 100 | You set all three yourself |
A free macronutrient calculator that quietly rounded a custom split to fit would be hiding an error rather than reporting one, so custom percentages that do not total 100 are refused and the page says which field is at fault.
Using it for fat loss or weight gain
As a macro calculator for fat loss, the higher-protein split is the conventional starting point, and a fat loss macro calculator elsewhere is usually doing the same thing: holding protein up while total energy comes down. The important part is that the deficit lives in the calorie target, not in the split. Rearranging percentages at a fixed calorie figure changes the grams and nothing else.
The same applies in the other direction. A gain goal is a larger calorie target entered here, not a different set of percentages.
Why grams can differ across splits at the same calories
Fat carries more calories per gram than protein or carbohydrate, so moving calories toward fat lowers the gram total for that share faster than the same percentage change would for protein or carbs.
Sources and limitations
Sources reviewed 27 August 2026. This page converts calorie targets into macro grams; it does not decide what eating pattern is medically appropriate for you.
It is an educational tool for healthy adults, not medical or dietary advice. It is not intended for children or adolescents, during pregnancy or breastfeeding, or for anyone managing a condition, an eating disorder or a medication that affects appetite, weight or metabolism.
Frequently asked questions
Does this tell me which macro split is best for me?
No. It converts a calorie target into grams using the split you choose. It does not diagnose needs, prescribe a diet, or replace professional nutrition advice.
How do I calculate my macros?
Start from a daily calorie target, split it into percentages for protein, fat and carbohydrate, then divide each share by its energy factor: 4 kcal per gram for protein, 9 for fat and 4 for carbohydrate. A 2,000 kcal balanced split gives 20 per cent protein, which is 400 kcal, which is 100 grams. That is the whole of the arithmetic this macros calculator performs.
What is the difference between a macro calculator and a calorie calculator?
A calorie calculator works out how many calories to eat from your body and activity. This macronutrients calculator takes that number as given and divides it into grams. If you do not have a calorie target yet, get one from the calorie calculator first, then bring it here.
What macros should I eat to lose weight?
A weight loss macro calculator usually raises protein relative to a balanced split, which is what the higher-protein option does at 30 per cent protein, 25 per cent fat and 45 per cent carbohydrate. The deficit itself comes from the calorie target you enter, not from the split: moving percentages around at the same calories does not create one.
Can I set my own percentages?
Yes. The custom split accepts any three percentages that total 100, and the page rejects a set that does not rather than silently normalising it. Percentages outside a plausible range are refused for the same reason.
Why do the grams change so much when I move fat?
Because fat carries 9 kcal per gram against 4 for protein and carbohydrate. Shifting a percentage point into fat buys fewer grams than the same point spent on either of the others, so the gram totals move further than the percentages suggest.