Keto Calculator for Weight Loss — Macros & Calorie Deficit

What Keto Macros Measure

The ketogenic diet is a very low-carbohydrate, high-fat diet designed to shift the body's primary fuel source from glucose to ketones — a metabolic state called ketosis. On a standard keto diet, approximately 70% of daily calories come from fat, 25% from protein, and only 5% from carbohydrates. This dramatic shift in macronutrient ratios forces the body to produce ketone bodies from fat stores, which can then be used as energy by the brain and muscles.

Keto macros are not a one-size-fits-all prescription. The ideal macronutrient split depends on your total daily energy expenditure (TDEE), body composition goals, activity level, and individual metabolic response. Our calculator first estimates your TDEE using the Mifflin-St Jeor equation, then applies the standard keto macro percentages to give you a personalized target in grams of fat, protein, and carbohydrates per day.

The Keto Macro Formula

Worked Example

A 35-year-old active male weighing 75 kg at 175 cm tall has a BMR of approximately 1,694 kcal using the Mifflin-St Jeor equation. With an activity factor of 1.55 (moderate activity), his TDEE is about 2,626 kcal per day. On standard keto macros, that translates to approximately 204 g of fat, 164 g of protein, and 33 g of carbohydrates per day. A 30-year-old sedentary female weighing 65 kg at 165 cm has a BMR of roughly 1,377 kcal, a TDEE of about 1,652 kcal (activity factor 1.2), and would target roughly 129 g fat, 103 g protein, and 21 g carbs per day.

Keto Macro Reference Table

Why Keto Macros Alone Are Not a Full Picture

While the standard 70/25/5 macro split is a useful starting point, several factors can significantly alter your individual keto needs. Your actual carb tolerance for maintaining ketosis depends on metabolic flexibility, muscle mass, and activity level — some people can stay in ketosis at 50 g of carbs per day, while others need to stay below 20 g. The protein ratio is also debated: too little protein risks muscle loss, while too much may theoretically reduce ketone production through gluconeogenesis, though this effect is often overstated in practice.

Additionally, the quality of your fat sources matters. Emphasizing monounsaturated and saturated fats from whole food sources (avocado, olive oil, nuts, seeds, fatty fish, coconut) is nutritionally superior to relying on processed keto-friendly packaged foods. Electrolyte balance — particularly sodium, potassium, and magnesium — requires attention on keto, as the diuretic effect of low insulin levels can deplete these minerals and cause the so-called "keto flu." A comprehensive approach to keto considers total calorie intake, food quality, hydration, electrolyte supplementation, and individual response, not just the macro percentages.

Known Limitations

• Individual keto macro needs vary significantly; some people require stricter carb limits (<20 g net carbs) to enter and maintain ketosis.
• The calculator assumes a standard 70/25/5 split; therapeutic keto for epilepsy uses different ratios (often higher fat, lower protein) and should only be followed under medical supervision.
• BMR estimation uses a male formula by default; female users may have slightly different metabolic baselines due to hormonal cycles and body composition differences.
• The formula does not account for body composition, medication interactions, thyroid function, or metabolic conditions that affect energy expenditure.
• Consult a healthcare provider before starting a ketogenic diet, especially if you have diabetes, pancreatitis, liver disease, or a history of disordered eating.