Keto Calculator - Daily Macros for Ketogenic Diet
Enter your stats below and this keto calculator will compute your Basal Metabolic Rate using the Mifflin-St Jeor equation, apply your activity multiplier to get your Total Daily Energy Expenditure, then split those calories into the classic ketogenic macro ratios. You get grams of fat, protein, and net carbs, plus a calorie target adjusted for your weight goal. Switch freely between metric and imperial units.
What is the ketogenic diet?
The ketogenic diet is a very low-carbohydrate, high-fat eating pattern that shifts your body from burning glucose to burning fat as its primary fuel. When carbohydrate intake falls below roughly 50 g per day (often 20-30 g for faster results), your liver begins producing ketone bodies from fatty acids. These ketones circulate in the blood and power the brain and muscles in place of glucose, a metabolic state called nutritional ketosis. The diet was first developed in the 1920s as a treatment for drug-resistant epilepsy and has since been studied for weight loss, type 2 diabetes management, and other conditions.
How this keto macro calculator works
The calculator uses the Mifflin-St Jeor equation to estimate your Basal Metabolic Rate, the calories your body burns at complete rest. Your BMR is then multiplied by an activity factor (1.2 for a sedentary lifestyle up to 1.9 for very high activity) to give your Total Daily Energy Expenditure. A calorie adjustment is applied for your goal: a 500 kcal or 750 kcal deficit for weight loss, or a 300 kcal surplus for muscle gain. That calorie total is then divided into macros. Net carbs are set by your chosen daily target (typically 20-30 g). Protein is calculated from your lean body mass at your chosen ratio (0.6-1.0 g per lb), or at a flat 25% of calories in auto mode. Fat fills all remaining calories at 9 kcal per gram.
Understanding net carbs vs total carbs
Net carbs are the carbohydrates your body actually digests and converts to blood glucose. The formula is: Net Carbs = Total Carbs minus Dietary Fiber minus Sugar Alcohols (erythritol and some others). Fiber passes through the gut largely undigested and does not raise blood sugar, which is why it is subtracted. Many processed keto products subtract sugar alcohols too, though the impact varies by type. Most keto research and clinical protocols target net carbs, not total carbs. For standard whole foods with minimal processing, the difference between total and net is mostly the fiber content of vegetables, nuts, and seeds.
Protein on keto: getting the amount right
Protein is the most misunderstood macro on a ketogenic diet. Too little and you lose lean muscle mass, especially in a calorie deficit. Too much and the body can convert excess amino acids to glucose through a process called gluconeogenesis, potentially blunting ketosis. The research-backed sweet spot is generally 0.6-1.0 g of protein per pound of lean body mass per day, with higher intakes for people doing resistance training or in aggressive calorie deficits. Calculating from lean mass rather than total weight avoids over-inflating the target for higher body-fat individuals. This calculator lets you choose a ratio or use the auto mode (25% of calories), which is the classic textbook keto split.
Frequently asked questions
See the FAQ section below for answers to common questions about the keto diet, how long ketosis takes, electrolyte needs, and how to adjust your macros as you progress.
Standard ketogenic macro ranges
| Macro | Grams | Calories | % of total calories | Target range |
|---|---|---|---|---|
| Fat | 100-165 g | 900-1485 kcal | 65-75% | Fills remaining calories |
| Protein | 60-120 g | 240-480 kcal | 20-30% | 0.6-1.0 g per lb lean mass |
| Net Carbs | 20-50 g | 80-200 kcal | 5-10% | Under 50 g for ketosis |
Typical macronutrient targets for a well-formulated ketogenic diet. Fat fills whatever calories remain after protein and carbs are set.
Frequently asked questions
How long does it take to enter ketosis?
Most people enter nutritional ketosis within 2-7 days of restricting carbs to under 50 g/day, depending on how depleted their glycogen stores become. Exercise accelerates the process by burning through stored glucose faster. Blood ketone meters (measuring beta-hydroxybutyrate) are the most accurate way to confirm ketosis; urine strips are less reliable after the first few weeks as the kidneys adapt.
How much weight can I lose on keto?
The first week typically shows a larger drop, often 2-5 lb, because glycogen stores (which bind water) are depleted. After that, sustainable fat loss follows the calorie deficit: roughly 1 lb of body fat per 3,500 kcal deficit. A 500 kcal/day deficit produces about 1 lb/week of fat loss over time. The calculator projects this trajectory in the 12-week chart.
Why are electrolytes important on keto?
When insulin levels fall on a low-carb diet, the kidneys excrete more sodium, which pulls water and other electrolytes with it. This causes the "keto flu" symptoms: headaches, fatigue, and muscle cramps in the first 1-2 weeks. Supplementing sodium (2-3 g/day), potassium (1-3 g/day from food), and magnesium (300-500 mg/day) typically resolves these symptoms. Bone broth, salt, leafy greens, and nuts are good whole-food sources.
Can I do intermittent fasting alongside keto?
Yes, and many people find the two complement each other. Ketosis suppresses appetite through ketone production and lower insulin levels, making time-restricted eating easier to sustain. A common approach is a 16:8 window (eating within 8 hours, fasting for 16). When combining the two, this calculator still applies: eat all your daily macros within your eating window.
What foods are keto-friendly?
Staples include fatty meats and fish, eggs, full-fat dairy (cheese, butter, cream), oils (olive, coconut, avocado), non-starchy vegetables (leafy greens, broccoli, cauliflower, zucchini), avocado, nuts, and seeds. Foods to avoid or minimise: bread, pasta, rice, potatoes, corn, fruit, legumes, most processed snacks, and anything with added sugar.
Does the keto calculator work for women differently?
The Mifflin-St Jeor equation includes a sex-specific constant (-161 for women, +5 for men) because women typically have less lean mass at the same height and weight. This means women will get a lower BMR and TDEE estimate, resulting in a lower calorie target. The protein and fat grams are then derived from that lower baseline. Everything else in the calculation is the same.
What happens if I eat too much protein on keto?
The body converts excess amino acids to glucose through gluconeogenesis. In practice, this process is demand-driven, not supply-driven, so moderate overages rarely knock most people out of ketosis. However, consistently doubling your protein target can reduce blood ketones measurably. If you are strict keto for therapeutic reasons, staying close to your protein target is worth the effort.
Sources
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 1990.
- Paoli A et al. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal of Clinical Nutrition, 2013.
- Volek JS, Phinney SD. The Art and Science of Low Carbohydrate Living. Beyond Obesity LLC, 2011.