Keto Macro Calculator

How Keto Macros Work

A ketogenic diet works by keeping carbohydrate intake low enough that your body shifts from burning glucose for fuel to burning fat, producing ketones in the process. Hitting that metabolic state depends less on total calories and more on the ratio between fat, protein, and carbs — which is why keto is usually planned around "macros" (grams of each macronutrient) rather than calories alone.

The standard keto split most people start with is roughly 70% of calories from fat, 25% from protein, and just 5% from carbs — typically landing carb intake somewhere between 20 and 50 grams a day, low enough to maintain ketosis for most people.

How to Use This Calculator

Enter your sex, age, weight, and height, then choose the activity level that best matches your week and your current goal. We first estimate your maintenance calories, then adjust for weight loss or gain, and finally split that calorie target into the standard 70/25/5 keto macro ratio in grams.

How We Calculate It

We calculate your Basal Metabolic Rate (BMR) using the Mifflin-St Jeor equation, the formula most commonly recommended by dietitians today for its accuracy across a wide range of body types. Multiplying BMR by an activity multiplier gives your Total Daily Energy Expenditure (TDEE) — the calories you burn in an average day including movement and exercise. For weight loss we subtract 500 calories a day from that (roughly a pound a week), and for weight gain we add 500. We then split the resulting calorie target into fat, protein, and carbs at 70%, 25%, and 5% of calories respectively, using 9 calories per gram of fat and 4 calories per gram of protein and carbs.

A Few Notes

These numbers are a solid starting point, not a medical prescription — individual factors like body composition, metabolic health, and how your body responds to carb restriction can shift what actually works best for you. Protein needs in particular can vary more than this fixed percentage suggests, especially for people who strength train regularly. If you have diabetes, kidney issues, or any other condition affecting how you process fat or protein, talk to a doctor or registered dietitian before starting a ketogenic diet.