Macro calculator for fat loss, with the math shown.

Start with your estimated maintenance calories (TDEE), not a calorie target that already includes a deficit. The default fat-loss option subtracts about 450 kcal from maintenance, so entering an already reduced target would apply another reduction.

You can switch body weight between pounds and kilograms. The protein control stays labeled in grams per pound, including when your weight is shown in kilograms; the calculator converts kilograms to pounds for that calculation.

Treat the defaults as editable calculator settings. They do not account for your medical history, training, preferences, or whether a particular target is suitable for you.

For the default fat-loss setting, the calculator uses these steps:

1. Target calories = estimated maintenance calories − 450 kcal, subject to the tool’s calorie guardrail.
2. Protein = body weight in pounds × 0.82 g per pound by default. You can change the factor.
3. Fat = 25% of target calories ÷ 9 kcal per gram.
4. Carbs = max(remaining calories after protein and fat, 0) ÷ 4 kcal per gram.

These are the calculator’s defaults, not a claim that this split is best for everyone. The other goal settings use maintenance calories as entered or add 150 kcal for muscle gain.

With estimated maintenance of 2,450 kcal, body weight of 150 lb, the fat-loss setting, and the default protein factor:

• Target: 2,450 − 450 = 2,000 kcal.
• Protein: 150 × 0.82 = 123 g, or 492 kcal.
• Fat: 25% of 2,000 = 500 kcal, which is about 55.6 g and displays as 56 g.
• Carbs: (2,000 − 492 − 500) ÷ 4 = 252 g, or 1,008 kcal.

The unrounded values total 2,000 kcal. Since the result tiles show whole grams, multiplying the displayed 56 g of fat by 9 gives 504 kcal; that small difference comes from rounding.