Macro Calculator a calorie target in grams
Enter your body, your activity and your goal. You get a daily calorie target split into grams of protein, fat and carbohydrate — with protein anchored to your weight.
Protein Comes First
It is set from body weight, then fat takes a share, then carbohydrate fills the rest.
Total Calories Still Rule
Hitting your macros only matters once the calorie total is right.
What is a macro calculator?
At a Glance
A macro calculator turns a daily calorie target into the three things you actually put on a plate: grams of protein, fat and carbohydrate. Calories decide whether weight moves; macros decide what the body does with the change — how much lean mass you keep, how full you feel, and how training goes.
Three steps, in a deliberate order.
Step one: the calorie target. Mifflin-St Jeor gives the basal rate, the FAO/WHO/UNU multiplier turns it into maintenance, and the goal applies a percentage adjustment. For the default persona that is 1,780 → 2,759 → 2,345 kcal at a 15 % deficit.
Step two: protein, from body weight. Protein is set per kilogram, not as a share of calories, because requirements track lean mass rather than intake. The International Society of Sports Nutrition position stand supports 1.4 to 2.0 g/kg for people who train, with the upper end favoured while cutting to protect lean mass.
protein g = body weight kg × g per kg, protein kcal = g × 4Setting protein as a percentage of calories is the common mistake: cut the calories and the protein target falls with them, which is precisely backwards.
Step three: fat, then carbohydrate takes the remainder.
fat g = (target × fat %) ÷ 9, carb g = (target − protein kcal − fat kcal) ÷ 4The 4/4/9 kcal-per-gram figures are the Atwater factors used on every nutrition label.
These are the values the calculator loads by default.
Find maintenance
Mifflin-St Jeor gives 1,780 kcal; × 1.55 for moderate activity = 2,759 kcal.
Apply the goal
A 15 % deficit: 2,759 × 0.85 = 2,345 kcal a day.
Set protein from body weight
80 kg × 2.0 g/kg = 160 g, which is 640 kcal — 27 % of the target.
Set fat as a share of calories
25 % of 2,345 = 586 kcal, and 586 ÷ 9 = 65 g of fat.
Give the rest to carbohydrate
2,345 − 640 − 586 = 1,119 kcal, and 1,119 ÷ 4 = 280 g of carbohydrate.
Three grams-per-day numbers look precise. They are a starting distribution, not a prescription.
Protein is the number worth hitting. It is the macro with the clearest evidence behind it: adequate protein in a deficit preserves lean mass, and it is the most satiating of the three. If you only track one thing, track this.
Fat has a floor, not a target. Below roughly 20 % of calories, hormone production and fat-soluble vitamin absorption start to suffer. Above that, the split between fat and carbohydrate is largely a preference and a training question — endurance and high-volume lifting run better on carbohydrate, and some people simply feel better higher-fat.
Carbohydrate absorbs the goal. Because it takes the remainder, it is the macro that moves most when you change the target. Going from cutting to maintenance on the default persona takes carbohydrate from 280 g to 357 g while protein does not move at all — which is exactly the intended behaviour.
Consistency beats precision. Being within about 10 g on each macro most days outperforms hitting them exactly on some days and abandoning the whole thing on others.
For the calorie target on its own, use the TDEE Calculator. To see how long a deficit will take, use the Calorie Deficit Calculator.
What a macro split cannot decide for you
This calculator is for informational purposes and is not medical advice or a diagnosis.
- It inherits the calorie estimate's error. The prediction equation behind the target sits within roughly 10 % for healthy adults, so verify against the scale over two weeks.
- Protein per kilogram uses total weight. At high body-fat levels, setting protein from lean mass or from a target weight gives a more sensible figure than total weight does.
- Food quality is invisible here. 280 g of carbohydrate from vegetables, fruit and grains is not the same meal as 280 g from sweets, even though the macro is identical.
- Micronutrients and fibre are not modelled. Macros are three numbers out of a much longer list.
- Medical conditions change the answer. Kidney disease, diabetes and several other conditions place real limits on protein or carbohydrate.
If you are managing a health condition, pregnant, or planning a substantial change in intake, discuss it with a doctor or a registered dietitian first.