Macro Calculator
How it works
We start from your calorie goal (BMR × activity, adjusted for your target), then set protein from your bodyweight (1.2–1.8 g/kg, capped at 35% of calories), fat at about 30% of calories, and fill the remainder with carbs.
The diet-style options shift that split: high-protein raises grams per kg, low-carb uses a fixed 30% protein / 30% fat / 40% carb ratio. Protein and total calories matter most — pick the split you can stick to. Calories per gram: protein 4, carbs 4, fat 9.
Frequently asked questions
What are macros?+
Macros (macronutrients) are protein, carbohydrates and fat — the three nutrients that supply calories. Protein and carbs have 4 calories per gram, fat has 9. Your macro targets split your daily calories across the three.
How are my macros calculated?+
We set protein from your bodyweight and goal, fat at about 30% of calories, and fill the rest with carbs. Choose a diet style (balanced, high-protein or low-carb) to shift the split.
How much protein do I need?+
Roughly 1.2–2.0 g per kg of bodyweight, higher when you're active or in a calorie deficit to protect muscle. This calculator scales protein to your weight and caps it at 35% of calories.
What's the best macro split?+
There's no single best split — total calories and protein matter most. Balanced (moderate carbs) suits most people; low-carb or high-protein can help with satiety. Pick what you can stick to.
Do I have to hit my macros exactly?+
No. Aim to get close, especially on protein. Flun logs your meals automatically and shows how your macros are tracking, so consistency is easy without obsessing over grams.