Keto Calculator

Your personal keto macros — net carbs, protein scaled to lean mass, and fat to fill your calories — for cutting, maintaining, or gaining on a ketogenic diet.

Sex
Age years
Height cm
ft in
Weight kg lb
Body fat %
Activity level
  • Sedentary — little or no exercise
  • Light — exercise 1–3 days/week
  • Moderate — exercise 3–5 days/week
  • Active — exercise 6–7 days/week
  • Very active — hard exercise or physical job
Goal
Net carbs per day g
Daily target
—kcal Your keto macros

Protein is scaled to your lean mass (0.8 g/lb) — that's why body fat matters — carbs stay fixed and fat fills the rest. Check with a clinician before keto if you have diabetes, kidney disease, or take blood-sugar or blood-pressure medication.

A ketogenic diet flips the usual fuel mix: carbohydrates drop low enough that your body switches to burning fat and ketones. Making that work day-to-day is a macro-arithmetic problem — and this calculator does the arithmetic properly, scaling protein to your lean mass instead of guessing from total weight.

How your macros are built

  1. Calories — Mifflin-St Jeor BMR × activity gives your maintenance; cutting takes −20%, gaining +10%.
  2. Net carbs stay fixed — default 25 g/day (adjustable 0–50 g). This is the lever that produces ketosis, so it doesn’t scale with calories.
  3. Protein scales to lean mass — 0.8 g per lb (1.76 g/kg) of lean body mass, the practical keto standard: enough to protect muscle in a deficit without stalling ketosis. This is why the calculator asks for body fat percentage.
  4. Fat fills the rest — whatever calories remain after carbs and protein come from fat, typically landing around 70–75% of intake.

Reading the result

The macro split looks extreme next to standard dietary advice — that’s the design, not an error. The percentages matter less than the gram targets: hit the carb ceiling, the protein floor, and use fat to control total calories. Hunger on keto is usually a fat-intake problem; a stall is usually a calories problem, not a carb problem.

Honest notes

Ketosis typically starts within 2–4 days under ~50 g net carbs, often with a rough adaptation week (“keto flu” — largely electrolytes; salt, potassium, and magnesium help). Long-term trials show keto performs about as well as other diets once adherence is equal — its advantage is appetite control for the people it suits. And the medical caveat is real: diabetes medication, kidney or liver disease, or pregnancy mean clinician supervision first.

Frequently asked questions

How are keto macros calculated?

Net carbs stay fixed (default 25 g — the level that keeps most people in ketosis), protein is set from your LEAN body mass at 0.8 g per pound (1.76 g/kg) to protect muscle, and fat fills whatever calories remain for your goal — a 20% deficit to cut, maintenance, or a 10% surplus to gain.

Why does the calculator need my body fat percentage?

Because protein needs scale with lean tissue, not total weight. Two people at 100 kg with 15% vs 40% body fat carry very different amounts of muscle; scaling protein to lean mass gives each the right target. If you don't know your body fat, estimate it with our body fat calculator first.

What are net carbs?

Net carbs = total carbohydrates minus fiber (and sugar alcohols), since fiber isn't digested into glucose. Keto practice typically caps net carbs at 20–30 g/day; the calculator lets you set your own allowance in that range.

Is keto safe for everyone?

No. People with diabetes on medication, kidney disease, liver conditions, or who are pregnant should only attempt keto with medical supervision — carb restriction can rapidly change blood sugar and blood pressure medication needs. For everyone else, it's a legitimate dietary pattern whose long-term results depend, like any diet, on adherence.

References