Macro calculator
Protein sized to your body, fat as a share of energy, carbohydrate as what remains — the split the app builds for you, shown with its arithmetic.
How this is calculated
protein_g = weight(kg) × protein_per_kg fat_g = kcal × fat% / 100 / 9 carbs_g = (kcal − protein_g×4 − fat_g×9) / 4
Four kilocalories per gram of protein and carbohydrate, nine per gram of fat — the Atwater factors. Carbs are computed from the already-rounded protein and fat grams, not from the raw values, so the three numbers on screen add back up to your target instead of missing it by a few calories.
Where the presets come from
Lose 2.0 g/kg and 25 % fat · maintain 1.6 g/kg and 30 % · gain 1.8 g/kg and 25 %. Protein is highest in a deficit on purpose: that is when lean mass is at risk, and it is the single dietary lever with good evidence behind protecting it (ISSN Position Stand on Protein and Exercise, 2017). The sliders are there because a preset is a starting point, not a prescription.
These are the same numbers and the same guards the Talk2Fit app applies when it builds your plan — the calculator is the app's own arithmetic, not a separate approximation.
Questions
Why is protein per kilo and not a percentage?
Because your muscles do not know what you ate. Protein need scales with body mass and training, not with the size of today's calorie target — a 40 % protein split means one thing at 3000 kcal and something useless at 1400. The ISSN position stand puts 1.4–2.0 g/kg for active people, and higher in a deficit.
Why do carbs come out as leftovers?
Because they are the flexible one. Protein protects muscle, fat has a floor you should not go under for hormones and absorption, and carbohydrate is what fuels the training in between. Fixing the first two and letting the third take the remainder is how the maths stays honest at any calorie level.
The carb number went negative — what does that mean?
That protein plus fat already cost more than the calories you set. It is not a rounding problem, it is an impossible plan: either the target is too low for your body weight or the fat share is too high. The calculator says so instead of printing a negative number.
Do I have to hit these exactly?
No. Protein is the one worth being consistent about; fat and carbs can move around it day to day and nothing bad happens. Consistency across a week beats precision on Tuesday.