Macro Calculator: Protein, Carbs & Fats by Goal

Macros — protein, carbs, and fat — are the three energy-providing nutrients. Hitting the right macro targets matters more than chasing the perfect 'clean eating' diet, especially if you're trying to lose fat while preserving muscle.

How to set protein, carbs, and fat targets

Protein first: 0.7-1.0 g per pound of body weight (1.6-2.2 g/kg) for active adults. Each gram of protein has 4 calories. Fat second: 20-30% of total calories (each gram has 9 calories), set higher (30-35%) on low-carb plans. Carbs fill the rest of the calorie target — each gram has 4 calories, so divide remaining calories by 4.

When to use this calculator

Use it any time your goal changes — cutting requires higher protein (preserves muscle in a deficit), bulking allows more carbs to fuel training. Use it after the first two weeks of a plan to recalibrate as your weight changes. Whole-food sources are better than the same macros from processed foods, but macro hitting is what drives body composition results.

Worked example

A 180 lb (82 kg) lifter cutting on 2,200 calories: 180g protein (720 cal, 33%), 60g fat (540 cal, 25%), 235g carbs (940 cal, 42%). Adjust upward 100-150g of carbs on training days, hold protein constant, and the same person can recomp without changing weekly average calories.

Limits and assumptions

Daily calories start from the Mifflin-St Jeor BMR for your sex, weight, height and age, multiplied by the activity factor you pick, then minus 500 for a weight-loss goal or plus 500 for a gain goal. The split applies fixed ratios per preset: balanced 30% protein / 40% carbohydrate / 30% fat, low-carb 40 / 20 / 40, high-protein 50 / 30 / 20 and keto 25 / 5 / 70. Grams use 4 calories per gram for protein and carbohydrate and 9 for fat, rounded to whole grams.

The 500-calorie adjustment is the same for everyone regardless of size, and there is no custom-ratio option. Fibre, meal timing and food quality are not modelled; treat the numbers as a starting target to adjust against real weight change.

Frequently asked questions

How much protein should I eat per day?

For active adults: 0.7-1.0 g per pound of body weight (1.6-2.2 g/kg). Higher when cutting (to preserve muscle) or training heavily. Above ~1.0 g/lb has diminishing returns for most people.

What macro split is best for fat loss?

High protein is the priority (preserves muscle in a deficit). After protein, the carb/fat split is largely personal preference — both work as long as you're in a calorie deficit.

What's the difference between IIFYM and clean eating?

If It Fits Your Macros (IIFYM) prioritizes hitting daily protein/carb/fat targets regardless of food source. Clean eating focuses on whole foods. Both work; IIFYM is more flexible, clean eating tends to be more nutrient-dense.

Macro Split Calculator