How to Calculate Net Carbs on the Keto Diet

If you’ve looked into keto at all, you’ve probably come across the term “net carbs.” Since it isn’t an entry on the nutrition information, you may not be familiar with it. In this post, we’ll cover why carb counts are important, why and how to calculate net carbs, what are good sources of carbs and how sugar alcohols are counted.

The Significance of Carbs on a Keto Diet

While carbohydrates are the least-consumed macro in keto, they are very important to track. In fact, the whole reason to track them is so that you don’t overdo carb consumption and prevent the metabolic state called ketosis.

Carbohydrates are composed of fiber, starch and sugar. Starch is a long chain of glucose (sugar) molecules that gets broken apart during digestion. On a standard diet, glucose is the main fuel and is stored in the liver and muscles. Anything beyond what they can hold gets converted to fat and stored.


On a keto diet, the whole point is to restrict carb consumption to stop running on glucose and switch to burning fat (stored energy). When you do that, you’re in ketosis.

Carbs vs. Net Carbs

It is important to understand how to count your carbs properly.

How to Calculate Net Carbs

It is simple to calculate net carbs from the nutrition information on any food. Simply subtract the grams of fiber from the grams of total carbohydrate, and that gives you the net carbs (in grams) for a single serving.

Why Calculate Net Carbs?

You may wonder why this calculation is necessary. Aren’t carbs just carbs to be restricted? Not exactly.

Starch and sugar are the carbohydrate components to be restricted because they contribute glucose energy to the system. Fiber, on the other hand, does not.

Fiber is made of insoluble and soluble fiber. The first does not break down, and the second breaks down so little that it isn’t worth counting. Fiber is not only very filling (when combined with fat); it is also very good for keeping your digestive system functioning well. That is why we calculate and count net carbs.

Target Levels for Net Carbs

Knowing how to calculate net carbs does no good if you don’t restrict them properly. A good range to aim for is 20 to 50 grams net carbs.

Most people who eat a keto diet stick to 20 to 30 grams to stay on the safe side, but those who test their ketone levels may find that they can eat up to 50 grams net and still produce ketones.

Additional Considerations

Some things are a little tricky and could use more explanation for you to get the most out of a keto diet.

Vegetable Carbs

Carb Sources

To avoid high sugar and/or starch content, you need to get your carbs mostly from leafy, flowering and fruiting vegetables. Root vegetables are high in starch (grains are even more so), and fruit is usually pretty high in sugar. Things like spinach, cauliflower and green beans are high in fiber, though. They taste delicious and fill you up while keeping carb counts low.

Small servings of nuts, seeds and select fruit are acceptable too. Be careful, though; net carb counts are higher in nuts and fruit. Check and control your serving sizes. For fruit, stick to small dark berries and don’t eat too much. Fruit like raspberries and blackberries are fairly tart and provide some great micronutrients.

Sugar Alcohols and Other Sweeteners

Natural and processed sugars (including honey and agave and maple syrup) are out on keto. There are many sweeteners available, but they can be misleading. While they are included in carb counts on labels and are different from regular sugars, they have effects that vary from nothing to a high-glycemic response.

There are natural, artificial and sugar-alcohol sweeteners. All the artificial sweeteners (aspartame, sucralose and saccharin) are to be avoided. They all have high GI scores, high net carbs or both.

Sugar Alcohols

Some people subtract sugar alcohols completely, but that can lead you astray. A safer bet is to subtract only half the sugar-alcohol count (if you are unsure) and avoid those with the highest glycemic index (GI).

Erythritol is a very good sugar alcohol that can be subtracted completely because its net carbs and glycemic response are extremely low. Xylitol and maltitol have higher glycemic responses and net carbs; restrict your use of them.

Natural Sweeteners

This group includes:

  • Stevia
  • Inulin fiber
  • Monk fruit
  • Allulose
  • Tagatose

All but the last one have zero glycemic effect, and tagatose is still very low (only a 3 on the glycemic index). They are all very low in carbs too. Any of these sweeteners are fine to use.

The Takeaway

Knowing how to calculate net carbs is an important part of implementing carbohydrate restriction on a keto diet. With this knowledge, you will make better progress toward your goals. Don’t count the fiber, be careful with the sweeteners and keto on!

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