What a keto macro split looks like
On a ketogenic diet the three macros sit in fixed proportions: carbohydrate is cut hard, protein is held at a moderate level, and fat covers most of the day's energy. In practice that means about 20 to 50 grams of carbs, protein near 1.2 to 2.0 grams per kilogram of body weight, and fat filling whatever calories are left. Those ranges come from Volek and Phinney's The Art and Science of Low Carbohydrate Living, the reference most low-carb guidance is built on.
Expressed as a percentage of calories, a typical keto day lands near 5 to 10 percent carbs, 20 to 25 percent protein, and 65 to 75 percent fat. The percentages shift a little with your body weight and calorie target, which is why this tool works in grams first.
How this calculator sets your keto macros
It runs four steps:
- Estimate maintenance calories from your TDEE, using the Mifflin-St Jeor equation for resting metabolism multiplied by an activity factor.
- Apply your goal: losing trims 500 calories a day, holding steady keeps maintenance.
- Fix carbs at your chosen limit (25 grams by default) and set protein from your body weight (1.6 grams per kilogram by default).
- Fill the remaining calories with fat, at 9 calories per gram.
A 500-calorie cut is floored at 1,200 calories a day, the point below which eating enough nutrients gets hard without medical supervision.
Carbs, protein, and fat on keto
Carbs are the lever that decides whether you stay in ketosis, so they stay low and fixed. Protein is set by body weight to protect muscle without knocking you out of ketosis. Fat is the fuel that fills the gap rather than a number to chase; on days you eat less fat, you simply eat fewer calories. If you want the same numbers for a standard diet, the macro calculator covers balanced, low-carb, and high-protein splits.
Who should be careful with keto
Keto is a large shift in how you eat, and it is not right for everyone. Anyone with kidney or liver disease, diabetes, or a history of disordered eating should speak to a doctor first, since very low-carb eating can affect blood sugar, medication needs, and electrolytes. The figures here are estimates for healthy adults and are not medical advice. Track how you feel in the first few weeks, and stop if something seems wrong.
