Estimates only, not medical advice. These are population formulas, and any one person can be well above or below them. If you are pregnant or breastfeeding, under 18, have diabetes, kidney disease, an eating disorder or another medical condition, or take medicine that affects weight, talk to your doctor or a registered dietitian before changing how you eat.
How the grams are worked out
Each macro's share of your calories is turned into calories, then into grams using the standard energy values: 4 calories per gram for protein and carbohydrate, 9 for fat.
Protein (g) = calories × protein % ÷ 4
Carbs (g) = calories × carb % ÷ 4
Fat (g) = calories × fat % ÷ 9
The three shares must add up to 100%. The calculator checks each one against the Acceptable Macronutrient Distribution Ranges (AMDR) for adults from the National Academies' dietary reference intakes (2005), as listed in Appendix 1 of the Dietary Guidelines for Americans 2020–2025:
| Macro | AMDR, % of calories | At 2,000 kcal |
|---|---|---|
| Protein | 10–35% | 50–175 g |
| Carbohydrate | 45–65% | 225–325 g |
| Fat | 20–35% | 44–78 g |
A split outside these ranges is not automatically unsafe, but it is outside what the guidelines describe, so the calculator flags it rather than refusing it.
Worked example: 2,000 calories
With the balanced split (20% protein, 50% carbs, 30% fat): protein is 2,000 × 0.20 ÷ 4 = 100 g, carbs 2,000 × 0.50 ÷ 4 = 250 g, and fat 2,000 × 0.30 ÷ 9 = 67 g. Over three meals that is about 33 g of protein, 83 g of carbs and 22 g of fat each. Switch to the higher-protein split (30 / 45 / 25) and it becomes 150 g protein, 225 g carbs and 56 g fat. This example is loaded when the page opens.
Choosing a split
- Balanced (20 / 50 / 30) sits near the middle of every range. A sensible default.
- Higher protein (30 / 45 / 25) helps if you lift weights or are eating in a deficit and want to hold on to muscle. Check the grams against the protein calculator; on a low calorie target, 30% may still be below what you need.
- Lower carb (25 / 45 / 30) keeps carbs at the bottom of the AMDR without leaving it.
- Endurance (15 / 60 / 25) leans on carbs for long training sessions.
Whatever the split, the Dietary Guidelines for Americans 2025–2030 say saturated fat should in general stay under 10% of daily calories, which is under 22 g at 2,000 calories.
Limits
- Grams are only as good as the calorie target. Start from a realistic one and adjust after 2 to 3 weeks.
- Food labels round, and 4/4/9 are averages, so tracked totals will never match exactly.
- If you have diabetes, kidney disease or another condition affected by diet, or are pregnant, a registered dietitian can set targets for you.
Sources checked October 2026.
Questions people ask
What are macros?
Macronutrients are the three nutrients that supply calories: protein and carbohydrate at about 4 calories per gram, and fat at about 9. Counting macros means setting a gram target for each, rather than only a calorie total.
What is a good macro ratio?
For adults, the National Academies set Acceptable Macronutrient Distribution Ranges (AMDR): 10 to 35% of calories from protein, 45 to 65% from carbohydrate and 20 to 35% from fat. Any split inside all three ranges is consistent with that guidance. The presets here all stay inside them; which one suits you depends on your training, your preferences and what you can stick with.
How do I turn percentages into grams?
Multiply your calories by the percentage, then divide by 4 for protein and carbs or 9 for fat. At 2,000 calories, 20% protein is 400 calories, which is 100 g; 50% carbs is 1,000 calories, or 250 g; and 30% fat is 600 calories, or about 67 g.
Can I use this for keto or a very low carb diet?
You can type any split, and the calculator will do the arithmetic. It will also tell you when a share falls outside the AMDR, as keto does for carbs and fat. Very low carb diets are a bigger change for people on diabetes or blood pressure medicine, so talk to your doctor first.
How many calories should my macros add up to?
Use your own calorie target. If you do not have one, the calorie calculator works it out from your height, weight, age, activity and goal. Then come back and enter it here.
Do I need to hit my macros exactly?
No. Food labels are rounded and portions vary, so hitting each number to the gram is not realistic. Treat the targets as a daily guide and look at your average over a week. Reaching your protein and keeping total calories near your target usually matter more than the exact carb and fat split.