Keto Macro Calculator

Calculate your ketogenic diet macros with the standard 70% fat, 25% protein, 5% carb split.

Results

Visualization

How It Works

The keto calculator returns daily fat, protein, and net-carb grams for a ketogenic diet — the canonical 70-75% fat / 20-25% protein / 5% carb split that keeps blood ketones above 0.5 mmol/L. Nutritional ketosis is defined by serum beta-hydroxybutyrate, not by macronutrient ratio per se: most healthy adults reach it in 2-4 days at <30 g net carbs (Volek & Phinney 2011), faster with concurrent exercise. Keto matches isocaloric mixed diets for fat loss in metabolic ward studies (Hall et al., Cell Metab 2016 — 4-week crossover, no fat-loss advantage when calories are matched) but consistently outperforms in free-living ad libitum settings due to suppressed appetite and stable blood glucose.

The Formula

BMR via Mifflin-St Jeor; TDEE = BMR * activity_multiplier; Target_Cal = TDEE * (1 - deficit%/100); Protein_g = body_kg * 1.6; Net_Carbs_g = 25 (fixed cap); Fat_g = (Target_Cal - Protein_g*4 - Net_Carbs_g*4) / 9

Variables

  • Net_Carbs — Total carbs minus fiber minus sugar alcohols (variable absorption — see net-carbs calc) — typically capped at 20-30 g/day
  • Protein_g — 1.4-1.7 g/kg body weight — enough to preserve muscle, low enough that gluconeogenesis stays minimal
  • Fat_g — Filler macro on keto: whatever calories remain after protein and carb floors are set
  • Beta-OHB — Beta-hydroxybutyrate, the ketone measured by blood meters; nutritional ketosis ≥0.5 mmol/L
  • deficit_pct — Percentage below TDEE (0% maintenance, 15-25% typical fat loss range)

Worked Example

75 kg male, TDEE 2,800, 20% deficit. Target = 2,240 kcal. Protein = 75 * 1.6 = 120 g (480 kcal). Net carbs capped at 25 g (100 kcal). Fat = (2,240 - 480 - 100) / 9 = 184 g (1,656 kcal). Final: 184F / 120P / 25C, ratio 74% / 21% / 5%.

Practical Tips

  • Sodium 3-5 g, potassium 3-4 g, magnesium 300-400 mg per day during the first 4 weeks. Glycogen depletion drops insulin, the kidneys dump sodium, and the keto-flu symptoms (headache, fatigue, cramps) are mostly an electrolyte problem — not a carb problem (Volek & Phinney 2011).
  • Protein 1.4-1.7 g/kg is the keto sweet spot for most lifters. The 'gluconeogenesis kicks you out of ketosis' fear is largely false: GNG is demand-driven, not supply-driven (Bray et al., Am J Clin Nutr 2012). High-protein keto preserves more lean mass than low-protein keto with no measurable difference in ketone levels.
  • Track ketones with blood (precision 0.1 mmol/L) or breath (acetone, fair correlation), not urine strips. Urine acetoacetate decays as you fat-adapt and stops correlating with serum BOHB after ~3-4 weeks.
  • Performance drops 5-15% in CrossFit/HIIT/sprint work for the first 4-6 weeks of adaptation (Burke et al., J Physiol 2017). Aerobic capacity at lower intensities recovers and often exceeds baseline. If you compete in glycolytic sports, time keto away from competition windows.
  • Targeted keto (15-30 g carbs 30-60 min pre-workout) preserves high-intensity output without disrupting overall ketosis for most people. Use dextrose or whole fruit, not maltodextrin gels which spike insulin harder.
  • Saturated fat is not a free-pass macro. Studies showing keto's metabolic benefits typically use a Mediterranean variant heavy in olive oil, fatty fish, nuts, and avocado — not bacon and butter. APOE4 carriers in particular respond poorly to high saturated fat regardless of carb level.
  • Re-introduce carbs gradually if cycling out: 20-30 g extra per day until you reach maintenance target. Sudden 200+ g carb loads after fat-adaptation cause severe water and glycogen rebound — 3-5 kg in 48 hours, mostly water.

Frequently Asked Questions

Is keto better than a flat low-cal diet for fat loss?

Calorie for calorie, no. Hall et al. (Cell Metab 2016) ran a 4-week metabolic ward crossover comparing isocaloric high-carb baseline vs ketogenic at 25 kcal/kg — fat loss was equivalent (actually slightly higher on the high-carb arm by ~0.5 kg). Keto's real-world advantage is appetite suppression: in free-living trials it produces ~200-300 kcal/day spontaneous deficit (Yancy et al., Ann Intern Med 2004).

Will too much protein kick me out of ketosis?

Almost never at sane intakes. Gluconeogenesis is regulated by demand (insulin/glucagon ratio, hepatic glucose need), not by amino acid availability. Multiple controlled studies (Bray 2012, Wilson 2020) showed 1.6-2.6 g/kg protein on keto produced equivalent ketone levels to lower-protein keto. The ratio drops because absolute protein rises, not because ketosis breaks.

Total carbs vs net carbs — which to track?

Net carbs for blood-glucose impact and ketosis maintenance. Total carbs as a sanity check on the upper bound. Fiber adds 0 to insulin response; erythritol adds 0; maltitol adds ~75% of sugar's response, so subtract it more conservatively (see Net Carbs calc for details).

How do I get into ketosis faster?

Combine fasting (16-24h water-only) with low-intensity exercise (walking, easy cycling) at the start. Glycogen depletion accelerates the metabolic switch from ~3-4 days of plain keto to ~24-36 hours. Add MCT oil (10-20 g) for direct ketogenic substrate — pure C8 (caprylic acid) raises BOHB faster than C8/C10 blends.

Can I build muscle on keto?

Yes, but harder than on a high-carb diet. Vargas et al. (J Int Soc Sports Nutr 2018) found keto + resistance training produced fat loss with maintained lean mass over 8 weeks but slower hypertrophy than the carb-fed group. For pure mass-building, keto is suboptimal; for cutting with muscle preservation it's competitive.

Is keto safe long-term?

Up to 2 years has good outcome data in metabolic disease populations: Hallberg et al. (Diabetes Ther 2018) tracked 262 type-2 diabetics on supervised keto with stable lipids, normal kidney function, and 1.3% A1c reduction at 2 years. Beyond 2 years, evidence thins. Contraindications: pancreatitis history, gallbladder issues, certain rare fatty acid oxidation disorders, pregnancy.

Why do my LDL numbers spike on keto?

Some people (lean mass hyper-responders, often with FH-like genetics) see LDL-C jumps of 50-100% on keto. Particle size and density (LDL-P, ApoB) usually shift to a less atherogenic pattern, but absolute particle count matters. Get an NMR LipoProfile or ApoB at 6 and 12 weeks; if ApoB rises significantly, swap saturated for monounsaturated fat (Mediterranean keto).

Does keto help with PCOS?

Yes, with consistent evidence. Mavropoulos et al. (Nutr Metab 2005) and follow-ups show 24 weeks of keto improves insulin sensitivity, reduces free testosterone, and restores menstrual cyclicity in roughly 50-60% of PCOS patients. The mechanism is insulin reduction, which lowers ovarian androgen synthesis.

Sources

Last updated: May 04, 2026 · Last reviewed: May 2026 — NutritionCalcs Editorial Team · About our methodology

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