Estimates from population equations — informational only, not medical advice.
About this tool
The Keto Macro Calculator is a free, in-browser tool that builds a ketogenic macro plan from your body stats. It estimates your basal metabolic rate with the Mifflin-St Jeor equation, scales it by your activity level to get TDEE, applies your deficit or surplus goal, then allocates macros keto-style: net carbs stay at your chosen cap (typically 20–50 g), protein is set from lean body mass (about 1.76 g per kg of lean mass, i.e. 0.8 g per lb), and all remaining calories come from fat.
Because protein is anchored to lean mass rather than total weight, the calculator needs a body-fat percentage — an estimate from a scale, calipers or a visual chart is fine. Everything runs locally in your browser and nothing is uploaded.
This tool is informational only — it is not medical advice.
Frequently asked questions
Why does fat get the leftover calories?
On keto, carbs are capped and protein is fixed by lean mass, so fat is the adjustable energy lever — the calculator converts whatever calories remain after protein (4 kcal/g) and carbs (4 kcal/g) into grams of fat at 9 kcal/g.
What are net carbs?
Net carbs are total carbohydrates minus fiber (and most sugar alcohols); most ketogenic plans cap them around 20–50 g per day to maintain ketosis, and you can set any cap up to 100 g here.
Why can I get a "calorie target too low" error?
If your deficit makes the calorie target smaller than the calories already needed for the fixed protein and carb amounts, fat grams would be negative — choose a smaller deficit or lower the carb cap rather than under-eating protein.
Is this medical advice?
No. These are informational estimates computed in your browser; a ketogenic diet is not appropriate for everyone (e.g. people with diabetes on medication, kidney or liver conditions, pregnancy), so consult a clinician before starting.
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