Formula, in Nutrition Planning

Macronutrient Ratio Formula

Set protein by body weight, fat by minimum essential threshold, fill the rest with carbs. Calorie targets first, ratios second — the ratio that worked at 2,500 calories doesn't work at 1,800.

4 variables. Published Mar 12, 2026. Updated May 10, 2026. By AI Fit Hub.

Education, not medical advice. The result comes only from the published formula and your inputs. How we check our formulas.

Formula

protein_g = mass_kg × protein_target_g_per_kg
fat_g     = mass_kg × fat_target_g_per_kg
carb_g    = (total_cal − protein_g·4 − fat_g·9) / 4

Variables

protein_g

Daily protein

Grams. 1.6 g/kg minimum for muscle retention, 2.2 g/kg upper bound for active lifters in a deficit. 4 cal/g.

fat_g

Daily fat

Grams. 0.6 g/kg minimum to support sex-hormone production; 1.0 g/kg is a more common comfortable upper bound. 9 cal/g.

carb_g

Daily carbohydrate

Grams. The remainder after protein and fat are set. 4 cal/g.

total_cal

Daily calorie target

From TDEE × goal multiplier (deficit, maintenance, surplus).

Step by step

1

Pin protein first. 1.8–2.0 g/kg is the working range for almost everyone training with intent.

78 kg × 1.8 = 140.4 g protein → 561.6 cal.
2

Set fat to its minimum healthy share — 0.8 g/kg is a sane default.

78 × 0.8 = 62.4 g fat → 561.6 cal.
3

Subtract protein and fat calories from the total target. The remainder belongs to carbohydrate.

2,303 cal − 561.6 − 561.6 = 1,179.8 cal → 1,179.8 / 4 = 294.95 g carbs.
4

Translate to a percentage if you want a ratio label. Note that the ratio will shift as calories move.

Protein 24% / Fat 24% / Carb 51%.

Worked example

78 kg adult, 2,303 cal target, 1.8 g/kg protein, 0.8 g/kg fat

Body mass (kg)

Daily calories

2,303

Protein target

1.8 g/kg

Fat target

0.8 g/kg

P 140.4 g (562 cal) | F 62.4 g (562 cal) | C 295 g (1,180 cal). Total 2,304 cal.

Macros: 140 P / 62 F / 295 C. Ratio 24/24/51. Protein and fat hit absolute targets first; carbs absorb calorie-target changes.

Common variations

Keto / low-carb: drop carbs to <50 g (or <5% of calories), bump fat to 1.5–2.0 g/kg. Protein stays anchored.

Endurance athlete: carbs to 5–10 g/kg around heavy training days, lower on rest days. Protein floor unchanged.

Cutting phase: hold protein at 2.2 g/kg even as total calories fall — the absolute number protects lean mass more than the ratio.

Run the numbers next

Nutrition Protein Intake Calculator
Get daily protein targets based on training level and goal.
Planning Calorie Deficit Calculator
Estimate required daily calorie deficit for a target timeline and bodyweight change.

Sources

Helms ER et al. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes , International Journal of Sport Nutrition and Exercise Metabolism
Morton RW et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength , British Journal of Sports Medicine