# What should my macros be?

Splits daily calories into grams of protein, carbohydrate and fat (4, 4 and 9 calories per gram) by the chosen percentages, and checks them against the adult AMDR ranges.

- Page: https://www.acalculator.org/health/macro-calculator
- JSON spec: https://www.acalculator.org/health/macro-calculator.json
- Version: 82794d893b34

## Default answer

Example with the default inputs (Daily calories Work them out, Sex Female, Age 30, Height 5 ft 5 in, Weight 150 lb, Activity Light: exercise 1 to 3 days, Goal Keep my weight, Carbs 50%, Protein 20%, BMR formula Mifflin-St Jeor): At 1,927 calories a day, eat about 96 g of protein, 241 g of carbs and 64 g of fat.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| known | Daily calories | Whether to work out your daily calories from your body and goal, or type them in. |
| calories | Calories a day | The calories you plan to eat each day. |
| sex | Sex | Sex at birth, which the body formulas use. |
| age | Age | Your age in whole years. |
| height | Height | Your height without shoes. |
| weight | Weight | Your body weight. |
| activity | Activity | How active you are in a usual week, which sets the multiplier on your BMR. |
| goal | Goal | Keep, lose or gain weight, which adds to or takes from your daily calories. |
| carbs | Carbs | The share of calories from carbohydrate. |
| protein | Protein | The share of calories from protein. |
| formula | BMR formula | The equation for basal metabolic rate: Mifflin-St Jeor (1990) or the revised Harris-Benedict (1984). |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| protein | Protein a day | Grams of protein a day: calories × protein share ÷ 4. |
| carbs | Carbs a day | Grams of carbohydrate a day: calories × carb share ÷ 4. |
| fat | Fat a day | Grams of fat a day: calories × fat share ÷ 9. |
| calories | Calories a day | The daily calories the grams are worked out from. |
| fatShare | Fat share | The share of calories from fat: 100% − carbs − protein. |
| proteinKcal | Calories from protein | Calories a day from protein. |
| carbsKcal | Calories from carbs | Calories a day from carbohydrate. |
| fatKcal | Calories from fat | Calories a day from fat. |
| ranges | Against the adult ranges | Whether each share is inside the adult AMDR: protein 10–35%, carbs 45–65%, fat 20–35%. |
| limit | Note | A warning when a loss goal, or typed calories, fall below the lowest intake the weight-loss guideline suggests. |

## Method

Protein and carbs in grams = calories × share ÷ 4; fat in grams = calories × (100% − carbs − protein) ÷ 9. Calories are typed, or TDEE (BMR × activity factor) ± the goal.

## Assumptions

- Protein and carbohydrate give 4 calories per gram and fat gives 9 (Atwater factors).
- Fat gets whatever share carbs and protein leave.
- The ranges are the adult Acceptable Macronutrient Distribution Ranges (IOM 2005): protein 10–35%, carbs 45–65%, fat 20–35%.
- Worked-out calories use Mifflin-St Jeor or the revised Harris-Benedict, the activity factors 1.2 to 1.9, and 500 calories a day per pound a week.
- This is an estimate for planning, not medical advice.

## Worked examples

1. known = body, sex = female, age = 30, height = 1.651, weight = 68.038856, activity = light, goal = maintain, carbs = 50, protein = 20, formula = mifflin gives calories = 1,926.737388, protein = 0.096337, carbs = 0.240842, fat = 0.064225, fatShare = 30%, ranges = All three are inside the adult ranges.. Source: Mifflin et al. 1990; 4, 4 and 9 calories per gram (USDA); hand calculation in content.mdx.
2. known = calories, calories = 2,400, carbs = 45, protein = 30 gives protein = 0.18, carbs = 0.27, fat = 0.066667, fatShare = 25%, fatKcal = 600. Source: 4, 4 and 9 calories per gram (USDA); hand calculation in content.mdx.
3. known = calories, calories = 1,800, carbs = 20, protein = 35 gives protein = 0.1575, carbs = 0.09, fat = 0.09, fatShare = 45%, ranges = Carbs 20% is under the 45% to 65% range. Fat 45% is over the 20% to 35% range.. Source: IOM 2005 AMDR (carbs 45–65%, fat 20–35%); hand calculation in content.mdx.
4. known = body, sex = male, age = 35, height = 1.778, weight = 81.646627, activity = moderate, goal = lose1, carbs = 40, protein = 30, formula = mifflin gives calories = 2,224.460212, protein = 0.166835, carbs = 0.222446, fat = 0.074149. Source: Mifflin et al. 1990; 500 calories a day for 1 lb a week; hand calculation in content.mdx.

## FAQ

### What are macros?

Macros (macronutrients) are the three nutrients that give most of the calories in food: protein, carbohydrate and fat. Protein and carbohydrate give 4 calories per gram, and fat gives 9. Counting macros means tracking grams of each, not only total calories.

### How do I calculate my macros?

Multiply your daily calories by the share for each macro, then divide by its calories per gram. At 2,000 calories with 45% carbs, 30% protein and 25% fat: carbs are 2,000 × 0.45 ÷ 4 = 225 g, protein 2,000 × 0.30 ÷ 4 = 150 g, and fat 2,000 × 0.25 ÷ 9 = 56 g.

### What is a good macro split?

For adults, the National Academies set Acceptable Macronutrient Distribution Ranges: 45% to 65% of calories from carbohydrate, 20% to 35% from fat and 10% to 35% from protein. The default here, 50% carbs, 20% protein and 30% fat, is inside all three. The calculator tells you when your split is outside a range.

### What is the best macro split for weight loss?

Total calories matter most for weight loss. A higher protein intake can help keep muscle while you eat less (International Society of Sports Nutrition, 2017). Pick a loss goal to lower your calories, then choose a split you can keep to.

### Why can I only set carbs and protein?

The three shares must add up to 100%, so fat gets whatever carbs and protein leave. If carbs and protein add up to more than 100%, there is no answer.

### Where do the daily calories come from?

Choose "I know them" to type your own number. Otherwise the calculator estimates your total daily energy expenditure (TDEE) from your sex, age, height, weight and activity with the Mifflin-St Jeor equation, then adds or takes away calories for your goal: 500 fewer a day for about 1 pound a week of loss.

## Sources

- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC: The National Academies Press; 2005 (Acceptable Macronutrient Distribution Ranges). https://www.nationalacademies.org/publications/10490
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025, Appendix 1 (macronutrient ranges for adults). https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf
- U.S. Code of Federal Regulations, 21 CFR 101.9(c)(1)(i)(C): general factors of 4, 4 and 9 calories per gram for protein, total carbohydrate and total fat. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-B/part-101/subpart-A/section-101.9
- 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. https://doi.org/10.1093/ajcn/51.2.241
- Roza AM, Shizgal HM. The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass. Am J Clin Nutr. 1984;40(1):168-182. https://doi.org/10.1093/ajcn/40.1.168
- Wishnofsky M. Caloric equivalents of gained or lost weight. Am J Clin Nutr. 1958;6(5):542-546. https://doi.org/10.1093/ajcn/6.5.542
- 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. https://doi.org/10.1186/s12970-017-0177-8
- Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults. Circulation. 2014;129(25 Suppl 2):S102-S138. https://pmc.ncbi.nlm.nih.gov/articles/PMC5819889/