How are my macros calculated?
Protein and fat use body-weight coefficients; carbohydrate uses the calories left over. These are fixed planning assumptions, not a clinically personalised nutrition prescription.
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Macro Calculator
Enter calories and body weight, or estimate calories from your body details. Your numbers update as you type.
Your daily macro split
Protein 1.6–2.2 g/kg body weight (sports nutrition consensus); fat 20–35% of calories; remaining calories from carbohydrates.
80 kg, maintenance and 2,000 kcal are editable starting inputs, not a recommendation.
How the macro calculation works
Mifflin–St Jeor estimates resting energy. An activity multiplier estimates daily energy. The calorie and macro choices below are this tool’s fixed planning assumptions, not individual medical advice.
BMR: 10 × weight (kg) + 6.25 × height (cm) − 5 × age + 5 (male) or −161 (female). TDEE = BMR × activity multiplier: 1.2, 1.375, 1.55 or 1.725.
Fat loss subtracts 400 kcal; muscle gain adds 250 kcal; maintenance uses TDEE. Protein: 2.0 / 1.8 / 1.6 g per kg for fat loss / gain / maintenance. Fat: 0.9 g per kg. Carbohydrate takes the remaining calories at 4 kcal per gram.
These coefficients are transparent defaults, not a promise of exact needs. The formula omits pregnancy, nursing, medical conditions and sport-specific demands.
Optional body-fat figures use a circumference equation with centimetre-based coefficients. Inch inputs are converted before calculation.
Questions before you start
Why do I need my weight if I know my calories?
This calculator sets protein and fat in grams per kilogram. Calories alone cannot determine those amounts without another assumption.
Will these numbers guarantee weight loss or muscle gain?
No. Energy equations are estimates and actual needs vary. Review changes with a qualified professional when needed, and do not treat a calculated deficit as a guarantee.
Why do calories and rounded grams differ slightly?
Grams are rounded for readability. Percentages use unrounded values, so the rounded grams may add up to a few calories more or less.
Are my inputs saved or sent anywhere?
No. Inputs stay in memory in this tab. This site uses Google Analytics for visits and interactions. Custom events contain only a fixed tool name, never body details or calculated numbers.
Build the training week too
Add your schedule and equipment to get a weekly training template alongside your calorie and macro estimates.
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