How to use the macro calculator
- Either enter your details (sex, age, height, weight, activity and goal) so the tool estimates daily calories, or type your own calorie target to skip the estimate.
- Choose a macro split: balanced, moderate, lower carb, higher carb, or custom percentages that add to 100.
- Optionally open the advanced options to set how many meals per day you eat.
- Read the grams of carbohydrate, protein and fat per day and per meal, along with the calories each one supplies.
Formula
Calories from a macro = daily calories x share of calories
Grams of carbohydrate = calories x carb share / 4
Grams of protein = calories x protein share / 4
Grams of fat = calories x fat share / 9
Estimated calories = Mifflin-St Jeor BMR x activity multiplier + goal adjustment
The 4, 4 and 9 are the standard Atwater general factors in kilocalories per gram. Labels may differ slightly because manufacturers can use specific factors. Grams are rounded to whole numbers after the exact calculation.
Worked example
For a 2,000 kcal target on the balanced 50/20/30 split, carbohydrate supplies 1,000 kcal (250 g), protein supplies 400 kcal (100 g) and fat supplies 600 kcal (66.7 g, shown as 67 g).
With the default profile (a 35-year-old female, 5 ft 6 in, 150 lb, lightly active, maintaining weight) the estimate is 1,914 kcal, which gives about 239 g of carbohydrate, 96 g of protein and 64 g of fat.
Choosing a goal of one pound a week of loss subtracts 500 kcal and gives 1,414 kcal before the split is applied.
What macros are
Macronutrients are the three nutrients that supply calories: carbohydrate, protein and fat. Alcohol also supplies calories but is not counted here. Tracking grams of each one is a way to put a calorie target into practical terms, such as how much protein to aim for at each meal.
Reference ranges used for notes
The tool gently notes when a split falls outside the Acceptable Macronutrient Distribution Ranges listed for adults: carbohydrate 45 to 65 percent of calories, protein 10 to 35 percent and fat 20 to 35 percent. Being outside a range is not an error. It means the pattern differs from the general reference, and a clinician or dietitian can help you decide whether that suits you.
Picking a split
There is no single best split. People pick based on preference, training and medical guidance.
- Balanced 50/20/30 sits in the middle of the reference ranges.
- Moderate 40/30/30 raises protein at the expense of carbohydrate.
- Lower carb 30/35/35 is below the carbohydrate reference range and is shown with a note.
- Higher carb 55/20/25 suits some endurance training patterns.
Related tools
Use the TDEE calculator to compare formulas for your calories, and the protein intake calculator to set protein from body weight instead of a percentage.
Assumptions and limits
- Calories are estimated with the Mifflin-St Jeor equation and a conventional activity multiplier. Typing your own target replaces that estimate completely.
- Calorie goals add or subtract a flat 250 or 500 kcal a day. Results vary and no weight outcome is promised.
- The tool will not suggest fewer than 800 kcal a day. Very low calorie plans need medical supervision.
- Fiber, alcohol, sugar alcohols and label rounding are not modeled.
- Information only. This is not medical or dietary advice, and it does not account for conditions such as diabetes, kidney disease or pregnancy.
Frequently asked questions
How many grams of protein, carbs and fat should I eat?
It depends on your calories, goals and health. This calculator shows the grams that result from a calorie target and a split you choose. It does not say which split is right for you, which is a question for a dietitian or doctor.
Why do my macros not add up exactly to my calories?
Grams are rounded to whole numbers, so the three totals can differ from the target by a few calories. The exact unrounded grams are shown in the steps.
Can I enter my own calories instead?
Yes. Type a target in the optional calorie field and the estimate is skipped. The target must be between 800 and 10,000 kcal a day.
Are the 4, 4 and 9 calories per gram exact?
They are the standard general factors used for labeling and planning. Real foods vary slightly, so a food log app can differ by a few percent from this arithmetic.
What happens with a custom split that does not add to 100?
The tool shows an error and does not guess. Carbohydrate, protein and fat percentages must total exactly 100 percent.