Macro Calculator
Turn your calories a day into grams of protein, carbohydrates and fat, and check the split against the ranges the National Academies set for adults.
Not sure? The maintenance calorie calculator estimates it.
Compare protein with your body weight
At 2,000 calories a day, eat about
100 g protein
250 g of carbohydrates and 67 g of fat. All three are inside the ranges the National Academies set for adults.
- Protein 20%
- Carbohydrates 50%
- Fat 30%
| Calories | Grams | |
|---|---|---|
| Protein: 20% of calories, 4 per gram | 400 | 100 g |
| Carbohydrates: 50% of calories, 4 per gram | 1,000 | 250 g |
| Fat: 30% of calories, 9 per gram | 600 | 67 g |
| Total | 2,000 |
| Nutrient | Share of calories | Grams a day |
|---|---|---|
| Protein | 10–35% | 50–175 g |
| Carbohydrates | 45–65% | 225–325 g |
| Fat | 20–35% | 44–78 g |
Saturated fat: at most 22 g a day, 10% of your calories, per the Dietary Guidelines 2025–2030.
This is general information, not medical advice. Talk to a doctor about your own numbers.
How this is calculated
Each gram of protein and of carbohydrate counts as 4 calories, each gram of fat as 9. These are the general factors the FDA allows for nutrition labels. So the calculator multiplies your calories by each share and divides by 4 or 9.
Example at 2,000 calories, 20% protein, 50% carbs and 30% fat: protein 2,000 × 20% = 400 calories ÷ 4 = 100 g; carbs 2,000 × 50% = 1,000 ÷ 4 = 250 g; fat 2,000 × 30% = 600 ÷ 9 = 67 g. Nutrition labels round their calories and may count some fiber at 2 calories a gram, so food diaries rarely match to the gram.
The ranges
The National Academies (then the Institute of Medicine) set Acceptable Macronutrient Distribution Ranges: the share of calories each nutrient can supply. For children they are different:
| Nutrient | Adults | Ages 4–18 | Ages 1–3 |
|---|---|---|---|
| Carbohydrates | 45–65% | 45–65% | 45–65% |
| Fat | 20–35% | 25–35% | 30–40% |
| Protein | 10–35% | 10–30% | 5–20% |
The three ready-made splits (balanced 50/30/20, higher protein 45/25/30, lower carb 45/35/20) all sit inside the adult ranges. They are examples, not a prescription. With your own split, the calculator says which nutrient falls outside a range.
Protein by body weight
The Recommended Dietary Allowance for protein is 0.8 g per kilogram of body weight a day for adults (0.36 g per pound): the amount that covers the needs of nearly all healthy people. At the reference weights that is 56 g for men and 46 g for women. The Dietary Guidelines for Americans 2025–2030, published in January 2026, set a higher goal of 1.2 to 1.6 g per kilogram (0.54 to 0.73 g per pound), adjusted to your calorie needs. Open “Compare protein with your body weight” to see both for your weight.
Carbohydrates and saturated fat
The Recommended Dietary Allowance for carbohydrates is 130 g a day for adults; the calculator notes when a split falls below it. The 2025–2030 Dietary Guidelines say saturated fat should in general not exceed 10% of daily calories, which is 22 g at 2,000 calories.
Calories come first: the maintenance calorie calculator estimates them, and the calorie deficit calculator lowers them for weight loss. If you are pregnant, breastfeeding, under 19 or have a medical condition, ask a doctor or registered dietitian about your numbers.
Sources
Checked against the sources below on .
- National Academies, Food and Nutrition Board: DRI tables, RDAs for macronutrients and Acceptable Macronutrient Distribution Ranges (from the 2002/2005 report)
- USDA and HHS: Dietary Guidelines for Americans, 2025–2030 (January 7, 2026), protein and saturated fat
- FDA, 21 CFR 101.9(c)(1)(i): 4, 4 and 9 calories per gram for protein, carbohydrate and fat
Questions people ask
How many grams of protein do I need a day?
The Recommended Dietary Allowance is 0.8 g per kilogram of body weight (about 0.36 g per pound), 56 g for men and 46 g for women at reference weights. The Dietary Guidelines 2025–2030 set a goal of 1.2 to 1.6 g per kilogram, about 82 to 109 g for a 150-pound adult.
What percentage of my calories should be carbs, fat and protein?
For adults the National Academies' ranges are 45 to 65% from carbohydrates, 20 to 35% from fat and 10 to 35% from protein.
How do I turn calories into grams?
Divide by 4 for protein and carbohydrates and by 9 for fat. 400 calories of protein is 100 g; 600 calories of fat is about 67 g.
What are good macros for 2,000 calories?
A split in the middle of the adult ranges, 50% carbs, 30% fat and 20% protein, is 250 g of carbs, about 67 g of fat and 100 g of protein. Many other splits also fit the ranges.
How many carbs a day is the minimum?
The Recommended Dietary Allowance for carbohydrates is 130 g a day for adults, 175 g in pregnancy and 210 g while breastfeeding.
How much saturated fat can I eat a day?
The Dietary Guidelines 2025–2030 say saturated fat should in general not exceed 10% of daily calories: 22 g at 2,000 calories, 18 g at 1,600.