Keto Ratio and Net Carbs Calculator
This keto ratio calculator works out net carbs and the ketogenic ratio (fat versus protein plus net carbs) from any nutrition label. The carb convention you pick is always displayed with the results, so fiber is never subtracted twice.
Calculated results
Convention: total carbs including fiber — fiber and excluded polyols have been subtracted.
Not all polyols are metabolically equivalent: the chosen convention remains an approximation.
The displayed ratio and energy measure neither blood glucose nor ketone bodies: no ketosis is guaranteed.
The classic ratio is a weight ratio (fat ÷ (protein + net carbs)), not calories. The result does not guarantee ketosis.
Method and limits
How to use this calculator
Copy the macros from your nutrition label: carbs, fiber, fat and protein in grams. Select the convention that matches your label — total carbs including fiber, or carbs already expressed as net. If the product contains polyols you want to exclude, enter their amount and turn on the exclusion. Net carbs, the ketogenic diet ratio and the indicative energy appear instantly, with the active convention recalled as a warning.
Fiber grams are subtracted from total carbs only when the entered carbs include them; polyols are excluded only per the selected convention. The ketogenic ratio divides grams of fat by the sum of protein and net carbs: R = F / (P + C_net).
Net carbs: two explicit conventions
Under the “total carbs including fiber” convention, net carbs are C_net = C_total − Fiber − P_excluded, where P_excluded covers the polyols you explicitly exclude. Under the “already net” convention the formula becomes C_net = C_net_entered − P_excluded: the manufacturer has already removed the fiber. Fiber cannot exceed total carbs in the first convention — the check raises a consistency error — and negative values block the calculation. The result always displays the active convention.
Ketogenic ratio and indicative energy
The classic ratio in grams is R = F / (P + C_net): a ratio of 2 means two grams of fat for one combined gram of protein and net carbs. Indicative energy follows the nutritional approximation E = 9F + 4P + 4C_net in kilocalories, and the fat energy share follows from it. These values serve to compare preparations, not to build regulatory labeling. The ratio is undefined when protein and net carbs are both zero — handled as an explicit error rather than a silent division.
Worked example
For a product listing 25 g of total carbs, 5 g of fiber, 150 g of fat and 30 g of protein (“total carbs including fiber” convention, no excluded polyols): net carbs 25 − 5 = 20 g; ratio 150 / (30 + 20) = 3.00:1; indicative energy 1,550 kcal; fat energy share 87.1%. Reproduce these values in the tool: you must get exactly the same results.
Assumptions and limits
Not all polyols are metabolically equivalent: subtracting 10 g of erythritol or 10 g of maltitol does not have the same effect on blood glucose. Per-macronutrient energy is a rounding convention (fiber is often counted between 0 and 2 kcal/g depending on the reference). Finally, the ratio measures neither blood glucose nor ketone bodies: it describes a composition, never a physiological state. These values serve to compare preparations, not to guarantee a metabolic outcome.
Frequently asked questions
Limits of use