Macro Calculator
Enter your stats, activity level, and goal to get a daily calorie target split into protein, fat, and carbohydrate grams, built on top of your estimated TDEE.
How It Works
The calculator first estimates your total daily energy expenditure (TDEE) using the Mifflin-St Jeor equation for BMR, multiplied by an activity factor. It then adjusts that number for your goal: about 20 percent below TDEE for weight loss, unchanged for maintenance, or about 12.5 percent above TDEE for weight gain.
From that calorie target, protein is set first using your chosen grams per kilogram of body weight (1.8 g/kg by default). Fat is set at 27 percent of total calories. Whatever calories remain become carbohydrates. Protein and carbohydrates provide 4 calories per gram, fat provides 9 calories per gram.
Worked Example
A 75 kg moderately active man aiming to maintain weight, with a TDEE of about 2700 calories and the default 1.8 g/kg protein target: protein = 1.8 x 75 = 135 g (540 calories). Fat = 27 percent of 2700 = 729 calories, or 81 g. Remaining calories for carbs: 2700 - 540 - 729 = 1431 calories, or about 358 g of carbohydrates.
Frequently Asked Questions
How is my calorie target calculated before the macro split?
The calculator first estimates your BMR with the Mifflin-St Jeor equation, multiplies it by an activity factor to get your TDEE, then adjusts that number based on your goal: about a 20 percent deficit for weight loss, no change for maintenance, or about a 10 to 15 percent surplus for weight gain.
Why does protein come first in the split?
Protein needs are best set relative to body weight rather than as a percentage of calories, since protein requirements for preserving or building muscle do not scale down just because someone is eating fewer total calories.
What protein target does this use by default?
It defaults to 1.8 grams per kilogram of body weight, inside the commonly cited range of 1.6 to 2.2 grams per kilogram for people who train regularly. You can enter your own value in that field if you want a different target.
How is fat calculated?
Fat is set at roughly 27 percent of total daily calories, within the commonly used 25 to 30 percent range, then converted to grams using 9 calories per gram of fat.
What happens to the remaining calories?
Whatever calories are left after protein and fat are assigned go to carbohydrates, converted to grams using 4 calories per gram. Carbohydrates act as the flexible remainder in this split.
Should I follow these numbers exactly every day?
Treat them as a starting target rather than a strict rule. Hitting your numbers within a reasonably close range on most days matters more than perfect precision on any single day.