Quick answer
Macros are the daily grams of protein, carbohydrate and fat. This calculator sets protein at 1.2, 1.6 or 2.0 g per kg, fat at 25% of calories, and carbohydrate as what remains. For 2,500 calories and 80 kg at 1.6 g per kg, that is 128 g of protein, 69 g of fat and 341 g of carbohydrate.1,2
Work out your macros
Enter your age, height and weight to see an estimate.
These are estimates from a published equation, not advice for you. They can be off by hundreds of calories for an individual. Ask your doctor first if you are pregnant or nursing, under 19, have a medical condition, or have ever had a difficult relationship with food.
Key facts
- NIH gives 1.2 to 2.0 g of protein per kg of body weight a day for athletes, and the ISSN says 1.4 to 2.0 g per kg is enough for most people who exercise to build and keep muscle.1,3
- Fat is fixed at 25% of calories, inside the 20% to 35% range in the National Academies' acceptable ranges for adults.2
- Food labels may work out calories with 4 calories per gram for protein, 4 for carbohydrate and 9 for fat, and this calculator uses the same factors.4
- The National Academies' ranges for adults are 10 to 35% of calories from protein, 45 to 65% from carbohydrate and 20 to 35% from fat.2
- The top protein setting here is 2.0 g per kg. The ISSN says 2.3 to 3.1 g per kg may be needed to keep lean mass in resistance-trained people who eat fewer calories than they use.3
How this macro calculator sets protein, fat and carbs
- Calories come first. The calculator estimates your resting energy, multiplies it by your activity level and applies your goal, the same steps as the TDEE calculator, and the result is the calorie total that the grams are built from.
- Protein is your weight in kilograms times the setting you choose: 1.2, 1.6 or 2.0 grams per kilogram. Each gram counts as 4 calories.4
- Fat is 25 percent of your calories, and each gram counts as 9 calories.4
- Carbohydrate gets whatever calories are left, at 4 calories a gram. If protein and fat already use up the day's calories, carbohydrate shows as zero and the calculator suggests less protein or a different goal.4
The percentages beside each result are rounded, so they can add up to 99 or 101. Pounds, feet and inches are converted to kilograms and centimeters before any arithmetic, and nothing you enter leaves your browser.
How much protein per kg does a macro calculator use?
| Setting | Protein a day | Calories from protein | Where it sits in the research |
|---|---|---|---|
| 1.2 g per kg | 96 g | 384 | The low end of NIH's 1.2 to 2.0 g per kg for athletes, and just under the ISSN's 1.4 to 2.0 g per kg |
| 1.6 g per kg | 128 g | 512 | Inside the ISSN's 1.4 to 2.0 g per kg, and the low end of the 1.6 to 2.2 g per kg that a review advises for natural bodybuilders in the off-season |
| 2.0 g per kg | 160 g | 640 | The top of both the ISSN and NIH ranges |
Two benchmarks sit at or just under the lowest setting: the RDA, and the amount advised for adults over 65.
The Recommended Dietary Allowance (RDA) for protein is 0.8 g per kg of body weight a day for healthy adults and 0.85 g per kg for teens. The ISSN says this amount is not enough for people in regular training.6,7
An international expert group on protein in older people (PROT-AGE) recommends at least 1.0 to 1.2 g per kg of body weight a day for adults over 65, and 1.2 g or more for those who exercise.8
All three settings sit above the RDA. They stop at 2.0 g per kg, though, and the sources describe higher amounts for some people: the ISSN says 2.3 to 3.1 g per kg may be needed to keep lean mass in resistance-trained people eating fewer calories than they use, and NIH says athletes might benefit from even more protein for short periods of intense training or when they eat less to reach a competition weight. A sports dietitian can set an amount like that. This calculator cannot.1,3
Why fat is 25% of calories and carbs take what is left
A fixed 25 percent keeps the fat figure inside the 20 to 35 percent range the National Academies set for adults, which the Dietary Guidelines for Americans reproduce. NIH gives the same 20 to 35 percent range for athletes.1,2
| Nutrient | Share of daily calories | Calories per gram |
|---|---|---|
| Protein | 10 to 35% | 4 |
| Carbohydrate | 45 to 65% | 4 |
| Fat | 20 to 35% | 9 |
Carbohydrate is left over rather than set, so it absorbs every change in calories. NIH gives typical carbohydrate for athletes as 3 to 10 g per kg of body weight a day. In the examples that follow, carbohydrate lands between 1.8 and 5.5 g per kg, and the lowest result comes from the highest protein setting at the lowest calories.1
The RDA for carbohydrate is 130 g a day for adults. At low calorie totals with the higher protein settings, this calculator can return less than that and does not warn you, as the last row of the next table shows.2
Macro calculator examples, worked through
| Person | Activity and goal | Protein setting | Calories | Protein | Carbohydrate | Fat |
|---|---|---|---|---|---|---|
| Man, 35, 180 cm, 80 kg | Moderate, stay the same | 1.6 g per kg | 2,720 | 128 g (19%) | 382 g (56%) | 76 g (25%) |
| Man, 28, 175 cm, 72 kg | Moderate, gain slowly | 2.0 g per kg | 2,862 | 144 g (20%) | 393 g (55%) | 80 g (25%) |
| Woman, 35, 165 cm, 65 kg | Moderate, lose slowly | 1.6 g per kg | 1,772 | 104 g (23%) | 228 g (52%) | 49 g (25%) |
| Woman, 28, 170 cm, 70 kg | High, gain slowly | 2.0 g per kg | 2,773 | 140 g (20%) | 380 g (55%) | 77 g (25%) |
| Man, 55, 178 cm, 92 kg | Light, lose slowly | 1.6 g per kg | 2,060 | 147 g (29%) | 239 g (46%) | 57 g (25%) |
| Woman, 50, 160 cm, 60 kg | Sedentary, lose slowly | 2.0 g per kg | 1,213 | 120 g (40%) | 107 g (35%) | 34 g (25%) |
The last row shows when a result needs a second look. Protein at 40% of calories is above the 35% top of the National Academies' range, and 107 g of carbohydrate is below the 130 g RDA. Switching the same woman to 1.2 g per kg gives 72 g of protein (24%), 155 g of carbohydrate (51%) and the same 34 g of fat.2
Macro calculator for muscle gain
For a gain, choose the gain slowly goal and a protein setting of 1.6 or 2.0 g per kg. The goal adds 10% to your daily calories. A review of nutrition for natural bodybuilders in the off-season advises novice and intermediate lifters to eat a surplus of about 10 to 20%, with protein of 1.6 to 2.2 g per kg, fat of 0.5 to 1.5 g per kg, and the remaining calories from carbohydrate, at least 3 to 5 g per kg. It says advanced lifters should be more conservative with the surplus.5
For the 28-year-old man in the examples, protein is 2.0 g per kg, fat works out to 1.1 g per kg and carbohydrate to 5.5 g per kg, each inside those ranges. The review is narrative, not a trial, and it covers natural bodybuilders, so it describes that group rather than everyone.5
The ISSN position stand says a sustained calorie surplus drives gains in lean mass, and that the size of the surplus and a person's training status both shape what the gains are made of. No calculator can say how much of a gain will be muscle.10
Macro calculator for women: what changes and what does not
Nothing in the macro split depends on sex. Protein follows body weight, fat follows calories, and sex enters only through the calorie estimate, where the equation uses minus 161 for women in place of plus 5. The NIH and ISSN protein ranges are given per kilogram for everyone who exercises.1,3,9
The evidence is thinner for women. The ISSN diets and body composition position stand notes a paucity of research on women and older populations, so any range, including the ones used here, rests on less direct evidence for them.10
What a macro calculator leaves out
- Food quality and fiber. The calculator counts grams and cannot tell a day of whole foods from a day of the same grams from other foods.
- Your body composition. Protein per kilogram of body weight gives a heavier person more protein, whatever share of that weight is muscle.
- Your real calories. Everything starts from the calorie estimate, which the National Academies' own equations miss by about 190 to 270 calories a day on average.11
- One right split. The ISSN found that a wide range of eating styles, from low-fat to low-carbohydrate, can give similar changes in body composition, and that long-term success depends on being able to keep to a plan.10
Who should ask a doctor before using macro targets
These targets are estimates for healthy adults, not advice for you, and the calorie total behind them can be off by hundreds of calories a day. Ask your doctor or a registered dietitian first if any of these apply.11
- You have kidney problems, or you have been told to limit protein.
- You have diabetes, or another condition where your doctor manages how much you eat or when.
- You are pregnant or nursing. The National Academies add extra energy to their equations for both, so neither the calorie total nor the split here applies.11
- You are under 19. The equation behind the calorie total was built on adults aged 19 to 78.9
- You have ever had an eating disorder, or tracking food makes you uneasy. NIMH says early detection and treatment are important for a full recovery.12
High-protein diets of two to three times the RDA do not appear to harm kidney function, bone health or hydration in healthy people, and trained adults eating up to about 3.3 g per kg a day for up to a year showed no change in kidney or liver markers. People with severely reduced kidney function may need to limit protein.6,7,8
Macro targets are a way to organize food, not a prescription. If you plan a large change in how you eat, ask your doctor first.
Questions people ask
What is a macronutrient calculator?
It turns a calorie total into grams of protein, carbohydrate and fat. Here protein is set by body weight, fat by a 25 percent share of calories and carbohydrate by what remains, using 4, 4 and 9 calories per gram.4
Which settings does a macro calculator for muscle gain need?
Choose the gain slowly goal, which adds 10 percent to your daily calories, and protein of 1.6 or 2.0 g per kg. A review for novice and intermediate natural bodybuilders in the off-season advises a surplus of about 10 to 20 percent and protein of 1.6 to 2.2 g per kg.5
Is a macro calculator for women different?
Only in the calorie estimate, where the equation uses minus 161 for women and plus 5 for men. Protein is per kilogram and fat is a share of calories for everyone. The ISSN notes that research on women is thinner.9,10
How many grams of protein, carbs and fat should I eat?
That depends on your calories and weight, which the protein carb fat calculator works out. At 2,500 calories and 80 kg it gives 128 g of protein, 341 g of carbohydrate and 69 g of fat at 1.6 g per kg. The National Academies' ranges for adults are 10 to 35 percent of calories from protein, 45 to 65 from carbohydrate and 20 to 35 from fat.2,4
What does it mean if my carbs come out under 130 g?
The RDA for carbohydrate is 130 g a day for adults. Low calories with a high protein setting can push carbohydrate below that, because carbohydrate is what is left after protein and fat. A lower protein setting or a different goal gives more room.2
Can I use a macro calculator if I have kidney problems or am pregnant?
Ask your doctor first. If your kidneys are not working normally, your doctor should set your protein amount. The National Academies also add extra energy to their equations for pregnancy and nursing, which this calculator does not include.11
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Sources
- National Institutes of Health, Office of Dietary Supplements. Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals. Updated April 1, 2024. Opened 2026-10-07.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. Appendix 1, Table A1-2: Daily Nutritional Goals, Ages 2 and Older. 9th edition. December 2020. Opened 2026-10-11.
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. Opened 2026-10-11.
- U.S. Food and Drug Administration. 21 CFR 101.9(c)(1)(i): Nutrition labeling of food, calorie content. Electronic Code of Federal Regulations. Opened 2026-10-11.
- Iraki J, Fitschen P, Espinar S, Helms E. Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review. Sports (Basel). 2019;7(7):154. Opened 2026-10-11.
- National Institutes of Health, Office of Dietary Supplements. Dietary Supplements for Exercise and Athletic Performance: Fact Sheet for Health Professionals. Updated April 1, 2024. Opened 2026-10-07.
- Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. Opened 2026-10-01.
- Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc. 2013;14(8):542-559. Opened 2026-10-07.
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. Opened 2026-10-11.
- Aragon AA, Schoenfeld BJ, Wildman R, et al. International society of sports nutrition position stand: diets and body composition. J Int Soc Sports Nutr. 2017;14:16. Opened 2026-10-11.
- National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Energy. Summary. Washington, DC: The National Academies Press; 2023. Opened 2026-10-11.
- National Institute of Mental Health. Eating Disorders. National Institutes of Health. Last reviewed December 2024. Opened 2026-10-11.
This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.