What this tool does
Enter sex, age, height, weight, activity, goal, and a carb cap. You get calories, protein grams, capped carbs, and fat grams that fill whatever calories remain. Calories use Mifflin-St Jeor TDEE with your fat-loss, maintenance, or gain adjustment — the same engine as the TDEE calculator. Protein uses the ISSN-style g/kg band (higher in a deficit). Carbs are a hard gram ceiling, not a percentage. If fat calories would go negative, the plan is incoherent — raise calories or lower protein or the carb cap.
How it works
Most keto calculators fix carbs first, then protein, then fat — this one follows that order. Nutritional ketosis patterns usually stay under ~50 g carbohydrate per day; many people use 20–30 g as a stricter cap. This tool counts total carbohydrate grams (same as typical food labels). If you track net carbs on labels, use the net carb calculator for subtraction math, then enter a cap that matches how you log in Cronometer or MyFitnessPal. The page does not measure blood ketones, prescribe electrolytes, or confirm ketosis.
Formula and methodology
Step 1 — TDEE = Mifflin-St Jeor BMR × activity factor (1.2–1.9). Step 2 — Calories = calorieTarget(TDEE, goal) with Protealpes educational floor (1,200 kcal women / 1,500 kcal men minimum). Step 3 — Protein g = midpoint of 1.8–2.4 g/kg if losing, else 1.6–2.2 g/kg (ISSN-style). Step 4 — Carb kcal = carbCap × 4. Step 5 — Fat g = max(calories − protein×4 − carbCap×4, 0) ÷ 9. Ketosis depends on glycogen, total carb intake, protein level, and individual response — macros alone cannot certify it.
How to interpret the result
If fat grams look very high, that is normal when calories are high and the carb cap is 25–30 g — fat fills the budget. If you feel flat in the gym, keto is optional; a moderate-carb split via the macro calculator is often easier to live with. Log these as gram goals, not percent sliders. Medical ketogenic therapy (epilepsy, etc.) is a supervised protocol — this page is not.
Example
An 80 kg, 180 cm, 30-year-old man at moderate activity: BMR ≈ 1,780 kcal, TDEE ≈ 2,760 kcal, fat-loss calories ≈ 2,210 kcal. Carb cap 30 g (120 kcal), protein midpoint of the deficit band ≈ 168 g (672 kcal), fat ≈ (2,210 − 792) ÷ 9 ≈ 158 g. Non-starchy vegetables still count toward the 30 g cap.
Common mistakes
- Entering a net-carb cap while logging total carbs from food labels.
- Eating “keto” packaged snacks that blow the cap in one serving.
- Protein so high that ketosis never arrives and blaming willpower instead of the math.
- Ignoring sodium, potassium, and magnesium in the first adaptation weeks.
- Using keto to hide a disordered restriction of food groups.
When this estimate may be off
- You are on SGLT2 inhibitors or other drugs with ketoacidosis risk — this is a clinical stop, not a macro tweak.
- Pancreatic, gallbladder, or lipid disorders under specialist care.
- Pregnancy or eating-disorder history.
- Body weight, height, or activity does not match a normal week.
- You wanted a moderate-carb cut — use the macro calculator instead.