Calculate net carbohydrates by subtracting fiber and sugar alcohols from total carbs. Essential for keto and low-carb diets.
Net Carbs Result
—g net carbs
Total carbs − fiber − adjusted sugar alcohols
Total Carbs
—
g
Fiber Deducted
—
g
SA Deducted
—
g
Calories from Net Carbs
—
kcal (×4 per gram)
Keto Compatibility
—
per serving
Net carbs = total carbs − fiber − (sugar alcohols × deduction factor). The FDA does not regulate the term “net carbs” — it’s an industry convention based on the science of glycemic impact.
What Are Net Carbs?
Net carbs represent the carbohydrates that your body actually digests and converts to glucose. The formula is simple: Net Carbs = Total Carbs − Fiber − Certain Sugar Alcohols.
Fiber passes through your digestive system without being broken down into sugar. Most sugar alcohols are only partially absorbed, producing a minimal blood sugar response compared to regular sugar.
Fiber is always subtracted — Both soluble and insoluble fiber are not digested into glucose.
Sugar alcohols vary — Erythritol has zero glycemic impact; maltitol is nearly as bad as sugar. The type matters enormously.
FDA doesn’t regulate “net carbs” — It’s an industry term, not an official nutritional designation. Be skeptical of “net carb” claims on packaging.
The “net carbs” concept was popularized by Atkins in the early 2000s. While not an official FDA term, the science is sound — fiber passes through undigested and most sugar alcohols have minimal glycemic impact. The key is knowing which sugar alcohols actually behave this way.
Sugar Alcohols Explained
Not all sugar alcohols are created equal. Their glycemic impact ranges from virtually zero (erythritol) to over half of regular sugar (maltitol). This table shows the key differences:
Sugar Alcohol
Glycemic Index
Calories/g
% Absorbed
Keto Verdict
Erythritol
0
0.2
0%
Best for keto
Xylitol
13
2.4
40%
Acceptable
Sorbitol
9
2.6
60%
Moderate caution
Isomalt
9
2.0
50%
Moderate caution
Maltitol
36
2.1
80%
Avoid on keto
Regular sugar
65
4.0
100%
Not keto
Maltitol is the worst sugar alcohol for keto. Its glycemic index (36) is over half that of table sugar (65). Many “sugar-free” products use maltitol — always check the label. A “sugar-free” candy bar with 20g of maltitol still spikes blood sugar almost as much as one with real sugar.
Net Carbs for Keto
For a standard ketogenic diet, the goal is to stay under 20–25g of net carbs per day. Here’s how that breaks down per food item, and some keto-friendly staples:
Per-food goal: Ideally under 5g net carbs per serving. This gives you room for 4–5 foods per day while staying under 20–25g total.
Avocado — 2g net carbs per half (9g total carbs − 7g fiber)
Egg — 0.5g net carbs each
Cheddar cheese — ~1g net carbs per ounce
Almonds — 2.5g net carbs per 28g (6g total − 3.5g fiber)
Broccoli — 4g net carbs per cup (6g total − 2g fiber)
Cauliflower — 3g net carbs per cup
Spinach — 0.4g net carbs per cup (raw)
Track Net Carbs Automatically with MacroLog
MacroLog calculates net carbs for every food — from barcodes, photos, or voice. No manual math needed.