How to Figure Net Carbs Easily and Accurately

October 19, 2025 •

4 min read

According to research from the National Institutes of Health, net carbs refer to the portion of carbohydrates that your body can fully absorb and use for energy. This guide will show you how to figure net carbs for both whole foods and packaged products, a skill essential for those following low-carb and keto diets.

Quick Summary

This article explains the simple formulas used to find net carbs, which represent digestible carbohydrates, by subtracting fiber and specific sugar alcohols from the total carbohydrate count on a nutrition label.

Key Points

Basic Formula: For whole foods, subtract the total dietary fiber from the total carbohydrates to get net carbs.
Processed Food Calculation: For packaged foods, also account for sugar alcohols, subtracting half for some types (maltitol, sorbitol) and the full amount for others (erythritol, allulose).
Find Label Info: Locate total carbs, dietary fiber, and sugar alcohols on a product's nutrition facts panel to perform the calculation.
Be Vigilant: The 'net carbs' label on products is not FDA-regulated, so always perform your own calculation to be accurate.
High-Fiber Foods: Incorporate foods naturally high in fiber and low in net carbs like avocado, berries, and green vegetables into your diet.
Impact on Health: Understanding net carbs is important for managing blood sugar levels, weight loss, and for those on ketogenic diets.

Understanding the Difference: Total vs. Net Carbs

Many people are familiar with the concept of counting carbohydrates for weight management or health reasons, but not all carbs are created equal. Total carbohydrates, as listed on a nutrition label, include starches, sugars, dietary fiber, and sugar alcohols. Net carbs, on the other hand, are the carbohydrates that your body can actually digest and convert into glucose, thereby affecting your blood sugar levels. This distinction is crucial for those on diets like the ketogenic diet, which strictly limits daily carb intake. Subtracting fiber and some sugar alcohols from the total carbohydrate count is the key to getting a more accurate picture of a food's true carbohydrate impact.

The Basic Formula: Calculating Net Carbs from Whole Foods

For unprocessed, whole foods like fruits, vegetables, nuts, and seeds, the calculation is straightforward. These foods contain naturally occurring fiber but no added sugar alcohols. To calculate their net carbs, you simply subtract the grams of dietary fiber from the total grams of carbohydrates.

Formula: Net Carbs = Total Carbs - Dietary Fiber

Example: A medium avocado contains 17.1 grams of total carbohydrates and 13.5 grams of fiber. The calculation would be: 17.1g (Total Carbs) - 13.5g (Fiber) = 3.6g Net Carbs. This simple subtraction provides a more useful number for tracking carb intake on a low-carb diet.

The Advanced Formula: Calculating Net Carbs in Processed Foods

Packaged and processed foods, especially those marketed as 'low-carb' or 'sugar-free,' often contain sugar alcohols to provide sweetness without the calories of sugar. The way you account for sugar alcohols in your calculation depends on the type. Some are largely indigestible, while others are partially absorbed and metabolized by the body.

For most sugar alcohols (e.g., Sorbitol, Maltitol, Xylitol): The body absorbs about half of their carbohydrates, so you should only subtract half of their total grams.
For Erythritol: This particular sugar alcohol is almost completely indigestible and has a minimal effect on blood sugar, so its total grams can be subtracted.
For Allulose: This rare sugar is not metabolized by the body and can also be fully subtracted.

Comprehensive Formula: Net Carbs = Total Carbs - Dietary Fiber - (1/2 * Sugar Alcohols*) - Allulose

* Only subtract half for sugar alcohols like sorbitol or maltitol. Fully subtract erythritol or allulose.

Example: Consider a keto bar with 23g total carbs, 9g fiber, and 11g of maltitol. The net carb calculation is: 23g (Total Carbs) - 9g (Fiber) - 5.5g (1/2 of 11g Maltitol) = 8.5g Net Carbs.

Potential Issues with Net Carb Counting

While calculating net carbs can be a useful tool for some, it's not a perfect science. The term 'net carbs' is not regulated by the FDA, and some companies may make misleading claims on their packaging. Furthermore, the body's individual response to certain fibers and sugar alcohols can vary. Some people may experience a slight blood sugar increase from sugar alcohols like maltitol, or digestive issues if too much is consumed. Therefore, it's always best to check the ingredients list and do the math yourself rather than relying solely on a product's 'net carb' claim.

Comparison of Common Carbohydrate Components

This table outlines how different types of carbs affect your net carb calculation and blood sugar.


Carbohydrate Type	Effect on Blood Sugar	How to Handle in Net Carb Calculation
Starches & Sugars	Significant increase	Fully counted in net carbs
Dietary Fiber	Minimal to no increase	Fully subtract from total carbs
Sugar Alcohols (Maltitol, Sorbitol)	Small to moderate increase	Subtract half from total carbs
Sugar Alcohols (Erythritol, Allulose)	Minimal to no increase	Fully subtract from total carbs

How to Find Fiber and Sugar Alcohols on a Label

To accurately calculate net carbs, you must locate the key information on the product's nutrition label.

Find the Total Carbohydrate section: This is the starting number for your calculation.
Locate Dietary Fiber: This sub-listing is located directly under the 'Total Carbohydrate' line on the label.
Find Sugar Alcohols (if applicable): This section may be listed directly below dietary fiber if the product contains them and makes a related claim, like 'sugar-free'. If not listed, you can check the ingredients for sugar alcohol names (e.g., erythritol, xylitol).

Conclusion

Understanding how to figure net carbs is a valuable skill for anyone managing their carbohydrate intake for diet or health purposes. The process is a simple formula of subtracting fiber and a portion of sugar alcohols from the total carbohydrate count. This method allows for a more accurate count of the carbohydrates that truly impact your blood sugar. However, due to individual variation and a lack of regulation, it is important to be a diligent label-reader and be aware of how your body responds to specific ingredients. By doing so, you can make more informed dietary choices and effectively manage your health goals.

For additional guidance and tools, an online net carb calculator can assist with the math. For example, Omni Calculator offers a user-friendly tool to help simplify the process.

High-Fiber Foods Low in Net Carbs

Here is a list of some naturally high-fiber, low-net-carb foods you can incorporate into your diet:

Avocado
Spinach
Broccoli
Cauliflower
Chia Seeds
Blackberries and Raspberries
Nuts (e.g., Pecans, Macadamia Nuts)
Mushrooms
Brussels Sprouts

Frequently Asked Questions

Net carbs are the carbohydrates your body can digest and use for energy, while total carbs include all carbohydrates, including fiber and certain sugar alcohols that are not fully absorbed.

Yes, dietary fiber is subtracted from the total carbohydrates when calculating net carbs because it is not digested by the body and therefore does not impact blood sugar levels in the same way as other carbs.

The effect of sugar alcohols depends on the type. Some, like erythritol, can be fully subtracted, while others, like maltitol, are partially absorbed and require only half their grams to be subtracted from the total carbs.

Calculating net carbs is crucial for a ketogenic diet because it helps track only the carbohydrates that can potentially disrupt ketosis, the metabolic state where the body burns fat for fuel.

Calculating net carbs is most important for processed or packaged foods that list dietary fiber or sugar alcohols. For whole foods, simply subtracting the fiber is sufficient.

No, the term 'net carbs' is not regulated by the FDA, so a product's claim might not be accurate. It's best to check the nutrition facts and ingredients list to do your own calculation.

For those on a low-carb diet, counting net carbs can be a useful tool for tracking and managing carbohydrate intake, which can support weight loss efforts.