Keto Calculator — Ketogenic Macro Targets

What Is This Calculator?

The ketogenic diet is a very low-carbohydrate, high-fat eating pattern that shifts the body's primary fuel source from glucose to ketone bodies — a state called nutritional ketosis. To enter and maintain ketosis, most people need to keep net carbohydrate intake below 20–50g per day.

How to Use This Calculator

Enter your details into the calculator above and click the calculate button. Results are instant and personalised to your specific inputs. All formulas are evidence-based and transparently explained.

What Is the Ketogenic Diet?

The ketogenic diet is a very low-carbohydrate, high-fat eating pattern that shifts the body's primary metabolic fuel from glucose to ketone bodies — a state called nutritional ketosis. When carbohydrate intake drops below approximately 20–50g of net carbs per day, liver glycogen depletes within 24–72 hours. The liver then begins converting fatty acids into ketone bodies (beta-hydroxybutyrate, acetoacetate, and acetone) to provide an alternative fuel for the brain and other organs.

The standard ketogenic macro distribution is approximately 70–75% of calories from fat, 20–25% from protein, and 5% or less from carbohydrates. Our calculator targets the strictest threshold — 20g net carbs per day — which reliably induces ketosis in most people. Some individuals can maintain ketosis at higher carb intakes (up to 50g) depending on insulin sensitivity, activity level, and individual metabolism.

How the Calculator Calculates Your Keto Macros

Net carbohydrates are fixed at 20g — the threshold most reliably associated with ketosis onset. Protein is calculated at 2.2g per kg of lean body mass (total weight minus estimated fat mass), which protects against muscle loss while in the significant caloric context of a ketogenic diet. Fat fills the remaining calories needed to hit your TDEE target adjusted for your goal. This "protein-forward" keto approach is supported by research showing that higher protein intakes on keto improve body composition outcomes without preventing ketosis.

Net carbs = total carbohydrates minus dietary fibre (and sugar alcohols in some frameworks). A 25g carbohydrate food with 8g of fibre has 17g net carbs. Most non-starchy vegetables, nuts, seeds, and dairy products fit comfortably within a 20g net carb budget when portions are managed.

The Evidence Base for Keto

Short-term evidence (up to 6–12 months) consistently shows keto is effective for weight loss, with particularly strong results in people with type 2 diabetes and insulin resistance. A 2020 review in Obesity Reviews found keto produced greater short-term weight loss than low-fat diets, though differences attenuated at 12+ months. Keto significantly reduces triglycerides, often raises HDL, and improves blood glucose and HbA1c in type 2 diabetics — effects beyond what weight loss alone explains.

Longer-term safety and sustainability evidence is more limited. Key practical considerations: the "keto flu" adjustment period (1–2 weeks of fatigue and brain fog, managed with electrolyte replacement), the need for careful micronutrient planning given the elimination of many plant foods, and the social and practical challenges of maintaining very low carb intake at restaurants and social events. For many people, a moderate low-carb approach (50–100g net carbs) produces most of the metabolic benefits with far greater sustainability.