How to use the macro calculator
- Set your daily calories. Enter a target you already use, or choose “Estimate them” and enter your age, sex, height, weight, activity and goal.
- Pick a macro split: balanced, higher protein, lower carb, or your own percentages (they must add up to 100%).
- Read your grams per day and, under “Meals per day,” set how many meals to split them across.
- Check the range comparison to see whether each share is within the recommended ranges for adults.
How macros work
Macronutrients are the three main nutrients that supply calories: protein, carbohydrate and fat. According to the USDA's National Agricultural Library, protein and carbohydrate provide 4 calories per gram and fat provides 9. That difference is why the same share of calories gives far fewer grams of fat than of carbohydrate.
grams = daily calories × share ÷ calories per gram
- share
- the macronutrient’s percent of calories, as a decimal (20% = 0.20)
- calories per gram
- 4 for protein, 4 for carbohydrate, 9 for fat
Worked example
With 2,000 calories a day and the balanced split:
- Protein: 2,000 × 0.2 = 400 calories ÷ 4 = 100 g
- Carbohydrate: 2,000 × 0.5 = 1,000 calories ÷ 4 = 250 g
- Fat: 2,000 × 0.3 = 600 calories ÷ 9 = 67 g
Spread over 3 meals, that is about 33 g of protein, 83 g of carbohydrate and 22 g of fat per meal.
If you let the calculator estimate calories instead, it uses the Mifflin-St Jeor equation. A 35-year-old woman who is 5′ 5″, weighs 150 lb and is moderately active has an estimated maintenance level of 2,133 calories; choosing “Weight loss” subtracts 500, for a target of 1,633. The balanced split then gives 82 g of protein, or 1.2 g per kilogram of body weight. The calorie calculator explains the equation and the limits of weight-loss estimates.
Acceptable Macronutrient Distribution Ranges (AMDR)
The National Academies set Acceptable Macronutrient Distribution Ranges as shares of calories associated with adequate intake of essential nutrients and a lower risk of chronic disease. The Dietary Guidelines for Americans, 2020–2025, list them by age:
| Age | Carbohydrate | Protein | Fat |
|---|---|---|---|
| 2–3 years | 45–65% | 5–20% | 30–40% |
| 4–18 years | 45–65% | 10–30% | 25–35% |
| 19 and older | 45–65% | 10–35% | 20–35% |
This calculator checks your split against the adult ranges. The same guidelines set a Recommended Dietary Allowance of 130 grams of carbohydrate a day and of 46 grams (women) or 56 grams (men) of protein for adults, and advise keeping saturated fat below 10% of calories. In 2024 a National Academies committee reviewed whether the ranges are still needed and noted limitations of the original work, so treat them as broad guardrails rather than precise targets.
Macros by calorie level
Grams per day for the balanced split (50% carbohydrate, 20% protein, 30% fat):
| Calories | Protein | Carbohydrate | Fat |
|---|---|---|---|
| 1,600 | 80 g | 200 g | 53 g |
| 1,800 | 90 g | 225 g | 60 g |
| 2,000 | 100 g | 250 g | 67 g |
| 2,200 | 110 g | 275 g | 73 g |
| 2,400 | 120 g | 300 g | 80 g |
| 2,600 | 130 g | 325 g | 87 g |
| 2,800 | 140 g | 350 g | 93 g |
| 3,000 | 150 g | 375 g | 100 g |
Balanced, higher-protein and lower-carb splits compared
The presets at 2,000 calories a day, and whether each share is inside the adult ranges:
| Split | Protein | Carbohydrate | Fat |
|---|---|---|---|
| Balanced | 100 g (20%) | 250 g (50%) | 67 g (30%) |
| Higher protein | 150 g (30%) | 225 g (45%) | 56 g (25%) |
| Lower carb | 150 g (30%) | 125 g (25%) * | 100 g (45%) * |
* Outside the adult range. The higher-protein preset keeps every share within the ranges by sitting at their edges. The lower-carb preset deliberately goes below the carbohydrate range and above the fat range; if that is your plan, it is worth discussing with a doctor or registered dietitian.
How much protein per day?
Protein needs are often described in grams per kilogram of body weight. The 2025–2030 Dietary Guidelines for Americans set protein serving goals of 1.2 to 1.6 grams per kilogram a day, adjusted to individual calorie needs. For a 150-lb (68 kg) person that is about 82 to 109 grams. When you use the estimate option, the calculator shows your protein in grams per kilogram so you can compare. If you have kidney disease or another condition that affects protein needs, follow your care team's advice.
To see how your body composition changes over time, use the body fat calculator, and for your resting energy needs, the BMR calculator.
Frequently asked questions
How do I calculate my macros?
Multiply your daily calories by each macronutrient's share, then divide by its calories per gram: 4 for protein and carbohydrate, 9 for fat. On 2,000 calories with 20% protein, protein supplies 400 calories, or 400 ÷ 4 = 100 g. Repeat for carbohydrate and fat, and check that the three shares add up to 100%.
What is a good macro ratio?
For most adults, a ratio inside the Acceptable Macronutrient Distribution Ranges is a sensible default: 45–65% of calories from carbohydrate, 10–35% from protein and 20–35% from fat. The balanced preset here (50/20/30) sits comfortably within them. No single ratio is best for everyone; food quality and total calories matter as well.
How much protein do I need a day?
The Recommended Dietary Allowance for adults is 46 grams a day for women and 56 grams for men, the amount that meets the needs of nearly all healthy people. The 2025–2030 Dietary Guidelines for Americans set higher protein serving goals of 1.2–1.6 grams per kilogram of body weight a day; for a 150-lb (68 kg) adult that is about 82 to 109 grams.
Should I count macros to lose weight?
Counting macros is optional. It is one way to plan meals around a calorie target and to check that protein, carbohydrate and fat stay within recommended ranges. Whether or not you count grams, the Dietary Guidelines for Americans emphasize nutrient-dense whole foods and limiting highly processed foods. If you have a medical condition such as diabetes or kidney disease, ask your doctor or a registered dietitian before changing your macros.
Is a low-carb diet outside the recommended ranges?
Often, yes. The lower-carb preset in this calculator (25% carbohydrate, 45% fat) falls below the carbohydrate range and above the fat range, and the calculator says so. Stepping outside the ranges is a deliberate choice some people make, but it is a good idea to discuss it with a health professional, especially if you have a health condition or take medicine.
How many grams of carbs should I eat a day?
Within the recommended range, carbohydrate supplies 45–65% of calories. On 2,000 calories that is 225 g to 325 g a day. The Recommended Dietary Allowance for carbohydrate for adults is 130 grams a day, well below that range at typical calorie levels.