Macro Calculator — Protein, Carbs, Fat in Grams

How macro splits convert from percentages to grams

To turn a calorie target into grams you need the conversion factors, which are the part most people never learn: protein provides about 4 calories per gram, carbohydrate about 4, and fat about 9. The arithmetic is then daily calories × percentage ÷ 100 ÷ calories per gram.

Worked through at 2000 calories on a 30/40/30 split of protein, carbohydrate and fat:

• Protein: 2000 × 30 ÷ 100 = 600 calories, ÷ 4 = 150 g
• Carbohydrate: 2000 × 40 ÷ 100 = 800 calories, ÷ 4 = 200 g
• Fat: 2000 × 30 ÷ 100 = 600 calories, ÷ 9 = 67 g

Fat yields far fewer grams than carbohydrate at a similar percentage

This catches people out on their first macro breakdown. Because fat carries 9 calories per gram against 4, the same share of calories produces a much smaller weight of food. In the example above, 40% carbohydrate becomes 200 g while 30% fat becomes only 67 g — a threefold difference in grams from a ten-point difference in percentage. Nothing is wrong; it is purely the calorie density doing the work, and it is worth internalising before you look at a target and assume it must be a mistake.

The hierarchy: calories, then protein, then preference

Total calories drive weight change, and that effect is far larger than anything below it. Protein is the split component with the best-supported specific benefit — chiefly retaining muscle while in a deficit, which is why cutting phases raise it.

Below those two, the carbohydrate-versus-fat division is largely a question of preference, satiety and what you will actually stick to. This deserves saying plainly, because macro discussion often implies every gram must be optimised: a split you can follow for months beats a theoretically superior one you abandon in a fortnight.

The presets reflect that range of preference — balanced (30/40/30), high protein (40/30/30), keto (25/5/70), low carb (35/20/45) and endurance (20/60/20) — or you can set your own, with the calculator checking that the three add up to 100%.

Protein often makes more sense per unit of bodyweight than as a percentage

Protein targets are commonly given as grams per unit of bodyweight rather than as a share of calories, and the two ways of expressing it can disagree badly.

The failure case is a low calorie target: 30% of 1200 calories is 360 calories, which is only 90 g of protein — likely short for most adults, even though the percentage looks respectable. The percentage stayed the same while the base it applied to shrank. A common rough guide is around 0.7 to 1 gram per pound of bodyweight, so a 200-pound person would be looking for roughly 140 to 200 g. Always sanity-check the gram figure against your bodyweight rather than trusting the percentage on its own.

Gram targets are approximate, not exact

The numbers imply a precision that home food tracking does not have. Labels carry legal rounding allowances, portions get estimated, and raw and cooked weights differ substantially because cooking drives off water — chicken weighed raw and the same chicken weighed cooked are not the same number.

Treat the targets as figures to land near rather than thresholds to hit. Being within five or ten grams is comfortably inside normal tracking error, and consistency over weeks matters far more than precision on any single day.

General fitness information only. This is not medical or dietary advice, and it is not appropriate for children. Anyone pregnant or breastfeeding, or managing a condition such as diabetes or kidney disease — where protein intake in particular may need to be controlled — should follow clinical guidance instead of a generic calculator.

To work out the calorie target to split in the first place, see the TDEE Calculator.