The ketogenic diet works because it forces your body to switch from burning glucose to burning fat — but that switch only happens when carbohydrate intake stays low enough, protein stays moderate enough, and fat supplies the bulk of your daily energy. This keto macro calculator turns your own height, weight, age, activity level and goal into a precise daily gram target for carbs, protein and fat, and then subtracts fiber to show your net carbs — the number that actually matters for staying in ketosis.
Adjust any field and every result updates instantly. The split used here is the standard clinical ketogenic ratio: about 7% carbs, 22% protein and 71% fat, which sits comfortably inside the widely cited 5–10% / 20–25% / 70–75% range.
How to Use
- Enter your Age in years. This feeds the Mifflin-St Jeor equation, the most accurate resting-metabolic formula used in clinical practice.
- Select your Biological Sex. The formula applies a small fixed adjustment — adding 5 kcal/day for men and subtracting 161 kcal/day for women.
- Type your Height in centimeters and your Weight in kilograms. These two numbers drive most of your resting metabolism.
- Choose your Activity Level honestly. Sedentary means a desk job with little exercise; light adds walking or light workouts 1–3 days per week; moderate is 3–5 days of exercise; active is 6–7 days; very active is daily hard training or physically demanding work.
- Pick your Goal. Lose applies a mild 15% calorie deficit, gain adds a 10% surplus, and maintain keeps you at your full TDEE.
- Optionally set your Fiber Intake. Most people eat 20–35 g of fiber per day; fiber does not raise blood glucose, so it is subtracted from total carbs to give net carbs.
The result card shows your basal metabolic rate (BMR), your total daily energy expenditure (TDEE), your target keto calories, and then the gram targets for carbs, protein and fat — with net carbs highlighted as the number to watch each day.
The Keto Macro Math
Your resting metabolism is estimated with the Mifflin-St Jeor equation:
- Men: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5
- Women: BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age − 161
You then multiply BMR by an activity factor (1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 active, 1.9 very active) to get TDEE, and apply your goal factor (0.85 lose, 1.0 maintain, 1.10 gain).
The gram targets use the standard energy density of macronutrients: carbohydrates and protein supply 4 kcal per gram, while fat supplies 9 kcal per gram. With a 2,238 kcal target, that works out to roughly 39 g carbs, 123 g protein and 177 g fat per day. Subtract your fiber — say 20 g — and your net carbs land around 19 g, which is the range most people need to stay in nutritional ketosis.
Why Net Carbs, Not Total Carbs?
Dietary fiber is a carbohydrate that human digestive enzymes cannot break down into glucose. It passes through the small intestine largely intact, feeding gut bacteria instead of blood sugar. That is why the keto community focuses on net carbs = total carbs − fiber: a 100 g avocado with 9 g total carbs and 7 g fiber contributes only about 2 g of net carbs, while a single slice of bread with 15 g total carbs and almost no fiber costs you nearly the whole day's budget.
Keep net carbs under 20–30 g per day if your goal is deep ketosis, or up to 40–50 g if you are using a more liberal low-carb approach and tracking your ketones.
Examples
Example 1 — A 30-year-old man aiming to lose weight. He is 175 cm, 75 kg, works a desk job but exercises moderately 3–5 days per week. His BMR is about 1,699 kcal, TDEE around 2,633 kcal, and with a 15% deficit his keto target is 2,238 kcal/day: 39 g total carbs (≈19 g net with 20 g fiber), 123 g protein, and 177 g fat. He aims for net carbs near 20 g.
Example 2 — A 40-year-old woman maintaining. At 165 cm and 60 kg with light activity, her BMR is about 1,270 kcal and TDEE about 1,747 kcal. Maintaining, her keto split is 31 g carbs, 96 g protein, 138 g fat — net carbs only about 6 g if she eats 25 g of fiber. This shows why keeping protein at the 20–25% band matters: too much protein can be converted to glucose through gluconeogenesis.
Example 3 — A large-scale stress test. Because the engine scales linearly, plugging in a very large body weight still produces consistent gram figures rather than an error — the math is just BMR × activity × goal, then the 4/4/9 conversion. Always sanity-check extreme inputs against a real body composition assessment.
FAQ
How many carbs should I eat per day on keto?
Most people stay in ketosis at 20–50 g of net carbs per day. Beginner keto typically targets under 20 g net carbs daily; more experienced or athletic people may tolerate 30–50 g. Net carbs = total carbs minus fiber, so high-fiber vegetables and small amounts of berries fit into the budget.
What should my protein intake be on keto?
Protein is usually set at 20–25% of calories, roughly 1.2–1.6 g per kg of lean body mass. Eating too little protein costs muscle; eating well above the 25% band may kick you out of ketosis because excess glucose can be produced from amino acids.
How much fat should I eat on keto?
Fat supplies 70–75% of daily calories on a standard ketogenic diet. It is your primary fuel source on keto, so do not skimp on it — avocados, olive oil, butter, fatty fish and nuts are the usual staples. Once you hit your calorie target for your goal, fat fills the remaining grams.
What is the difference between keto macros and regular macros?
A regular balanced split is roughly 50% carbs / 20% protein / 30% fat. A ketogenic split flips that: 5–10% carbs, 20–25% protein, 70–75% fat. The goal is not just weight loss but a metabolic state — ketosis — where the liver produces ketone bodies from fat for fuel.
How do I know if I am in ketosis?
Blood ketone meters are the most reliable; a beta-hydroxybutyrate reading of 0.5–3.0 mmol/L indicates nutritional ketosis. Urine strips and breath meters are cheaper but less precise. You may also notice reduced hunger, increased focus, and the "keto flu" in the first 1–2 weeks as you adapt.
Should I count total carbs or net carbs?
For keto, count net carbs (total carbs − fiber). Fiber does not raise blood glucose or insulin, so it should not count against your carbohydrate budget. Some people also subtract sugar alcohols, but those vary in digestibility — treat them cautiously.
Is the keto diet safe for everyone?
Keto is not appropriate for everyone. People with pancreatitis, liver failure, certain thyroid or adrenal conditions, type 1 diabetes, or women who are pregnant or breastfeeding should consult a clinician first. If you take diabetes medication, monitor glucose closely because dosages often need adjustment.
Disclaimer
This keto macro calculator is provided for informational purposes only and is not medical advice, diagnosis, or a treatment plan. Macronutrient estimates are based on the Mifflin-St Jeor equation and a standard ketogenic split; individual results vary by body composition, genetics, medication and health status. Always discuss major dietary changes — especially the ketogenic diet — with a qualified healthcare professional or registered dietitian, particularly if you have diabetes, kidney disease, are pregnant or breastfeeding, or take regular medication.