Net Carbs Calculator

Quickly calculate net carbs from total carbs, fiber, and optional sugar alcohols. Install the PWA for fast, offline use or embed the widget on your site.

Subtract Sugar Alcohols?
Enter label values; we’ll subtract fiber and (optional) sugar alcohols.

Net Carbs

0g

Embed this calculator on your site (widget & API)

Understanding Net Carbs

“Net carbs” are the carbohydrates your body can digest and convert into energy. Many low-carb and keto approaches estimate net carbs using a simple formula: net carbs = total carbohydrates − dietary fiber − sugar alcohols (sugar alcohols are optional because different products are absorbed differently). Use this calculator to prefill the numbers from any nutrition label and see a rounded, one-decimal-place result instantly.

How to use it: enter the grams of total carbohydrates and dietary fiber from the package. If the label lists sugar alcohols like erythritol, xylitol, or maltitol, turn on the toggle and enter those grams too. The result updates without reloading the page. If you’re on mobile, you can add the app to your Home Screen as a PWA to use it offline in grocery stores. Developers and bloggers can also embed a compact widget or call a simple JSON API to show net carbs under recipes and product reviews.

What are Net Carbs?

Net carbs estimate the portion of carbohydrates that meaningfully impacts blood sugar. Fiber is subtracted because it is not digested into glucose. Some people also subtract sugar alcohols since several are incompletely absorbed.

Why is Dietary Fiber Subtracted?

Most dietary fiber passes through the digestive system without being broken down. As a result, many low-carb frameworks remove fiber from total carbs to better reflect usable carbohydrates.

What about Sugar Alcohols?

Sugar alcohols (e.g., erythritol, xylitol, maltitol) are sweeteners that are only partially absorbed. Some count them fully, some subtract them. This tool lets you choose by toggling the sugar alcohol field.

Articles & Guides

What Are Net Carbs?

A quick, practical explainer—why net carbs matter and how they differ from total carbs.

Embed & API Info

Embeddable Widget

Copy and paste the snippet below into your site. Adjust the parameters to prefill values or theme.

Copy this code:
<script src="https://netcarbscalc.com/embed.js?tc=30&df=15&sa=4&theme=dark"></script>
Parameters
  • tc: Total Carbohydrates (grams)
  • df: Dietary Fiber (grams)
  • sa: Sugar Alcohols (grams)
  • theme: light or dark

Styling & more information on the developers page.

Developer API

Get a free API key at signup, then call the endpoint:

GET https://netcarbscalc.com/api?tc=30&df=10&sa=5&key=YOUR_API_KEY

See full docs at developers.