Macro Calculator

Estimate how many grams of protein, carbohydrates, and fat to eat each day. The calculator starts from your daily calories for your goal and splits them using ranges recommended for healthy adults.

An estimate for healthy adults

These formulas don't apply to people under 18, during pregnancy or breastfeeding, or with medical conditions that affect metabolism or weight. Talk to a doctor or registered dietitian before changing how you eat.

Calories (kcal/day)

2,123

Protein: 106 g
Fat: 71 g
Carbohydrates: 265 g

Results are estimates for information only and do not constitute financial, medical, or legal advice.

How it works

First, the calculator estimates your daily calories for your goal (Mifflin-St Jeor, your activity level, and a moderate change if you want one). Then it splits them by percentage and converts each part to grams: protein and carbohydrates have 4 calories per gram, and fat has 9.

The formulas

Protein (g) = calories × % ÷ 4 · Carbs (g) = calories × % ÷ 4 · Fat (g) = calories × % ÷ 9

Worked example

2,000 calories a day with the balanced split (20% protein, 30% fat, 50% carbohydrates).

Protein: 2,000 × 0.20 ÷ 4 = 100 g.
Fat: 2,000 × 0.30 ÷ 9 ≈ 67 g.
Carbohydrates: 2,000 × 0.50 ÷ 4 = 250 g.

Sources

Institute of Medicine (National Academies).Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids(acceptable macronutrient distribution ranges).
Mifflin MD, St Jeor ST, et al.A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990.

Frequently asked questions

What are macros?

Macronutrients are the three nutrients that give you calories: protein and carbohydrates (4 calories per gram) and fat (9 calories per gram). Counting macros means planning how many grams of each you eat.

Which split should I choose?

All three options stay within the ranges the US National Academies consider acceptable for adults: 10–35% of calories from protein, 20–35% from fat, and 45–65% from carbohydrates. The best split is one you can keep up and that fits your health. A registered dietitian can help you adjust it.

Do I need to hit my macros exactly?

No. They are a guide, not a rule. Being close most days matters more than being exact, and the overall quality of what you eat matters too.