What this tool does
Net carbs are a counting convention, not a third macronutrient. This page does the subtraction so you can stay under a cap you already chose.
How it works
Net = max(total − fiber − sugar alcohols, 0). We do not half-count maltitol or guess glycemic index.
Formula and methodology
Net carbs (g) = total carbohydrate − fiber − sugar alcohols.
How to interpret the result
A bar that is 20 g total, 12 g fiber, 4 g erythritol prints 4 g net. If the “fiber” is chicory syrup that wrecks your gut, the math can still be “correct” and the food still a bad idea.
Example
Sweet potato is not a “net carb food” in the bar sense — you eat the whole tuber. Use the sweet-potato guide for food, this tool for labels.
Common mistakes
- Subtracting fiber twice (once in the app, once in your head).
- Treating net carbs as calorie-free.
- Using this to justify a dozen “keto” cookies.
When this estimate may be off
- Labels that hide syrups as “soluble fiber.”
- Whole meals with no label — weigh the food instead.