How to Calculate the Percent of Total Carbohydrates From Sugar

Carbohydrates aren't just one simple nutrient. So that's why the number of total carbohydrates you see on a food's nutrition facts label includes the sugar, fiber, starch as well as sugar alcohols.

Food labels also include the total added sugars to help you stay under 10 percent of calories from added sugars, per recommendations from the Dietary Guidelines for Americans 2020-2025.

If you're trying to reduce your sugar intake, knowing what percentage of your carbohydrate intake is sugar allows you to track how you're doing and adjust your eating habits if necessary. The nutrition facts label on a product has all the numbers you need to do some simple math to get your answer.

Read the nutrition label and find the line for the "Total Carbohydrates" and the line for "Total Sugars." The total carbohydrates will have both a percentage and a number in grams. Find the grams of total carbohydrates and the grams for total sugars.

Let's use this example: A label lists 28 grams of total carbohydrates and 6 grams of total sugars.

Divide the number of grams of total sugars by the number of grams from the total carbohydrates line.

For this sample label, you would divide 6 by 28 to get 0.214.

Move the decimal point two spaces to the right or multiply by 100, if you prefer using an equation, to get you the percent form of the number.

Using the 0.214 from Step 2, you'll end up with 21.4 percent of the total carbohydrates coming from sugar.

Sugar alcohols and fiber are also listed on nutrition labels, but these nutrients are not digested the same or used by the body in the same way as sugars and starches.

Sugar alcohols sweeten foods without adding calories because they can't be fully digested, according to the Cleveland Clinic. Common sugar alcohols include xylitol, sorbitol, erythritol and mannitol.

Fiber can be in the form of soluble fiber or insoluble fiber and is found in foods like fruits, vegetables, whole grains and legumes. The small intestine can't break down and absorb fiber the same way it does sugars and starches, so fiber doesn't affect blood sugar levels in the same way, per the Centers for Disease Control and Prevention (CDC).

To calculate the total carbohydrates that will affect your blood sugar — which are also called net carbs — just subtract the fiber and sugar alcohols from the total carbohydrates.

So if a food has 30 grams of total carbohydrates, 5 grams of fiber and 3 grams of sugar alcohols, then the number of carbohydrates affecting your blood sugar would be 30 grams (total carbohydrate) - 5 grams (fiber) - 3 grams (sugar alcohols) = 22 grams net carbohydrates.