Macro Calculator
Estimate your daily calories and grams of protein, carbs and fat. Enter your details, pick a goal and adjust the macro split.
How the macro calculator works
Macros, short for macronutrients, are protein, carbohydrate and fat. This calculator first estimates how many calories your body uses at rest (basal metabolic rate) with the Mifflin-St Jeor equation, then multiplies by an activity factor to get your maintenance calories. A weight goal adds or removes calories, and your chosen split turns the calorie target into grams.
The default split is 25% protein, 50% carbohydrate and 25% fat. The Dietary Guidelines for Americans list acceptable ranges for adults of about 10 to 35% of calories from protein, 45 to 65% from carbohydrate and 20 to 35% from fat. You can read them on dietaryguidelines.gov.
This is an educational estimate, not medical advice. Talk to a doctor or registered dietitian before changing your diet, especially if you have a health condition.
The formulas
Example: A 30-year-old man who weighs 170 lb, is 70 in tall and exercises 1 to 3 days a week has a BMR of about 1,737 calories and maintenance calories of about 2,389. With a 25/50/25 split that is about 149 g of protein, 299 g of carbohydrate and 66 g of fat a day.
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Frequently asked questions
What are macros?
Macros are the three main nutrients that provide calories: protein and carbohydrate with 4 calories per gram each, and fat with 9 calories per gram.
How accurate is a macro calculator?
It is an estimate. Real calorie needs vary with muscle mass, genetics, sleep and daily movement. Track your weight for a few weeks and adjust the target if needed.
Which equation does this use?
The Mifflin-St Jeor equation for resting energy, multiplied by an activity factor. The 500 and 300 calorie adjustments are common rules of thumb, not medical prescriptions.
What macro split should I choose?
The default 25/50/25 sits inside the Dietary Guidelines ranges. Athletes and people with medical needs may use different splits with professional advice.
Is this medical advice?
No. It is for general education only. Ask a doctor or registered dietitian for personal advice.
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