How to use the macro calculator
- Choose Male or Female and US or Metric units. Your numbers convert when you switch.
- Enter Age, Height, and Weight, then pick your Activity level and Goal.
- Tap a diet preset or move the Carbs, Protein, and Fat sliders. The other two sliders shift so the total stays at 100%.
- Read your daily calories and grams of each macro, then pick 3 meals or 3 meals plus 2 snacks for the per-meal table.
How the macros are worked out
BMR comes from the Mifflin-St Jeor equation, times your activity factor gives TDEE, and the goal adds or subtracts calories. Weight-loss goals are held at 1,500 calories for men or 1,200 for women (or maintenance if that is lower), and a note says when that applies.
Each macro's calories are the daily calories times its share, and grams are those calories divided by 4 for carbs, 4 for protein, and 9 for fat. The presets, as carbs / protein / fat, are Balanced 40 / 30 / 30, Standard 50 / 20 / 30, Low carb 25 / 40 / 35, Keto 5 / 25 / 70, and High protein 30 / 40 / 30. Standard sits inside the National Academies ranges for adults: carbs 45% to 65%, protein 10% to 35%, fat 20% to 35%.
A percentage split ignores your size, so the tool also shows protein per kilogram and compares it with the 0.8 g per kg Recommended Dietary Allowance and the 1.2 to 1.6 g per kg in the 2025 to 2030 Dietary Guidelines for Americans.
Worked example
The starting inputs are a 30-year-old man, 5 ft 10 in and 175 lb, lightly active, with the goal Maintain weight and the Balanced split. His TDEE is 2,420, so daily calories are 2,420. Carbs at 40% are 968 calories, or 242 g. Protein at 30% is 726 calories, or 182 g. Fat at 30% is 726 calories, or 81 g. Protein is 2.3 g per kg, which the tool flags as above the 1.2 to 1.6 g per kg range. In the 3-meal table, lunch gets 40% of the day: 968 calories, 97 g carbs, 73 g protein, and 33 g fat.
Limits and edge cases
The calorie number is an estimate, and a percentage split is a starting point, not a prescription. Ages 15 to 100 are accepted, though the equation was built from adults aged 19 to 78. The keto preset and the fast weight-loss goal suit few people, so check with a doctor or dietitian first, especially in pregnancy or with a health condition.
For the calorie number alone, use the calorie and TDEE calculator. To base protein on lean mass, try the body fat calculator or lean body mass calculator. For food ideas, read macros explained.
Frequently asked questions
How do I calculate my macros?
Start with your daily calories: your TDEE, adjusted for your goal. Multiply by each macro's percentage, then divide by the calories per gram: 4 for carbs, 4 for protein, and 9 for fat. For 2,420 calories at 40% carbs, 30% protein, and 30% fat, that is 242 g, 182 g, and 81 g.
How much protein do I need per day?
The Recommended Dietary Allowance is 0.8 grams per kilogram of body weight, enough to avoid deficiency. The 2025 to 2030 Dietary Guidelines for Americans suggest 1.2 to 1.6 grams per kilogram for most adults. This tool shows your protein per kilogram so you can check both.
What macro split is best for weight loss?
No split works alone, because a calorie deficit is what drives weight loss. A higher protein share helps you feel full and keep muscle while you lose weight. Pick the carb and fat balance you can stick to.
Is the keto preset safe?
The keto preset is 5% carbs, 25% protein, and 70% fat. It is very low in carbs and does not suit everyone, including people with pancreatitis, liver disease, or fat metabolism disorders, or who are pregnant. Check with a doctor first.
Sources: Mifflin et al., Am J Clin Nutr 1990; National Academies, DRI for Macronutrients; MedlinePlus, Dietary Guidelines 2025 to 2030.