How we calculate it
The calculator starts from your daily calorie target (if you don't know yours, try our BMR and calorie calculator first) and splits those calories across the 3 macronutrients based on your chosen goal, using the most common ratios recommended in nutrition plans: fat loss (40% protein / 35% carbs / 25% fat, prioritizing satiety and muscle preservation during a calorie deficit), maintenance (30% / 40% / 30%, a balanced split) and muscle gain (30% / 45% / 25%, with more carbs to fuel intense training).
Converting to grams
Protein and carbs provide 4 kcal per gram, while fat provides 9 kcal per gram — so the same percentage of calories works out to a much smaller amount of grams for fat than for protein or carbs.
These are general reference ratios — individual needs vary a lot based on activity level, health conditions and food preferences; consult a dietitian for a personalized plan.
Frequently asked questions
Why does the split change based on goal?
During fat loss, more protein helps preserve muscle mass and increases satiety in a calorie deficit; during muscle gain, more carbs supply energy to sustain higher-volume/intensity training and optimize recovery.
Do these ratios work for everyone?
They're a reasonable starting point for most healthy people, but high-performance athletes, people with specific metabolic conditions (diabetes, kidney disease) or very specific goals generally benefit from a personalized split from a sports or clinical dietitian.