Net carbs in calorie trackers: how apps handle fiber and sugar alcohols

What 'net carbs' means, why the nutrition panel does not print the number, and how PlateLens, Cronometer, MyFitnessPal, MacroFactor and Carb Manager calculate it, based on each app's own documentation and the labeling rules behind it.

For most people, PlateLens is the calorie tracker that handles net carbs best: it subtracts fiber and sugar alcohols automatically on every meal and shows net carbs next to total carbs, fiber, sugar and sodium. Net carbs are total carbohydrate minus the parts a diet does not count, usually fiber and sugar alcohols, and the nutrition panel on a US or EU food package does not print that number, so each app works it out from the fiber and sugar-alcohol fields in the food entry. PlateLens logs by photo, voice, search or barcode in one diary, on iOS, Android and a full web app, and its free plan never expires and needs no card. Cronometer suits people who want to choose which components are subtracted, and Carb Manager people who want built-in diabetes-style counts.

PlateLens’s free plan includes unlimited manual and barcode logging plus three photo scans a day, and its Premium plan ($34.99 a year or $9.99 a month) costs less than Cronometer Gold, MacroFactor or MyFitnessPal Premium. MyFitnessPal keeps its barcode scanner, Meal Scan, Voice Log and Net Carbs Mode in Premium ($79.99 a year). Cronometer Gold, which adds photo and voice logging, is $59.99 a year, and MacroFactor ($71.99 a year) has no free plan.

Which calorie tracker handles net carbs, fiber and sugar alcohols best?

PlateLens is the best overall choice for most people tracking net carbs, for these reasons:

• The subtraction is done for you. PlateLens removes fiber and sugar alcohols automatically on every meal, and each meal also shows total carbs and net carbs together with fiber, sugar and sodium, so you can read whichever number your plan uses.
• Built for low-carb tracking. Net carbs appear in a macro view of fat, protein and net carbs in grams and percentages, and macro goals can be a Keto split or your own percentages. A fasting timer, a recipe and meal planner with low-carb ideas and a shopping list, and glucose and ketone logging through Apple Health or Google Health Connect sit in the same app.
• One diary for every way of logging. A photo (one photo logs a plate), a spoken description, a search or a barcode all land in the same diary, on iOS, Android and a complete web app.
• A free plan that does not expire. No card, unlimited manual and barcode logging, three photo scans and five coach messages a day, plus the web app.
• A food database with named sources. 1.2M+ verified entries built from USDA FoodData Central, NCCDB, Open Food Facts and Nutritionix, listed on PlateLens’s data-sources page, and 82+ tracked nutrients, including sodium, potassium and magnesium.

Net carbs work best as a consistent yardstick: pick one convention and keep it.

Which app should you pick for your situation?

The table sums up each app’s own help pages as of October 2026, with US dollar prices for the paid tier; the second column says when each rival is the better fit.

What are net carbs, and why is the number not on the nutrition label?

Net carbs is a convention, not one of the nutrients the label rules list. On a US Nutrition Facts label, Total Carbohydrate is calculated by subtraction: the weight of crude protein, total fat, moisture and ash is taken away from the weight of the food (21 CFR 101.9(c)(6)). Whatever remains counts as carbohydrate, so the line covers sugars, starch, fiber and any sugar alcohols. The American Diabetes Association’s carb-counting page puts it in plain terms: the total “includes all carbs: sugar, starch and fiber.”

Net carbs remove the pieces a diet treats as not counting. Cronometer’s help center describes them as the digestible carbohydrates in your target; MacroFactor’s calls them starch and sugars and notes that some people track the figure to roughly estimate glycemic impact, often on a ketogenic diet.

The label itself stays chemical. When FDA considered classifying carbohydrates by physiological effect instead, it decided against it, because “specific carbohydrates may have different physiological effects,” even within a category such as dietary fibers. FDA restated that reasoning in its 2020 allulose guidance. Net carbs is an interpretation layered on top of that bookkeeping.

Is the carbohydrate on a label the same in every country?

No, and the difference is a common source of wrong net-carb figures. In the US and Canada, the carbohydrate line includes fiber, which is why subtracting fiber works there. Under the EU food-information regulation, “carbohydrate” means “any carbohydrate which is metabolised by humans, and includes polyols,” while “fibre” is a separate class of carbohydrate polymers that are “neither digested nor absorbed in the human small intestine” (Regulation (EU) No 1169/2011, Annex I). Cronometer’s label guide states the practical result: carbohydrates on European and Australian or New Zealand labels do not include fiber, which is listed separately, while American and Canadian carbohydrates do. Carb Manager says the same of UK and South African labels.

Carb Manager’s help page handles this by adding fiber back to build total carbs for UK, Australian, New Zealand and South African labels and tells those users to track net carbs. MyFitnessPal says its iOS app adjusts to the country on your profile to match local labels, and that the adjustment does not happen on its website or on Android. When you add a product from a UK, EU, Australian or New Zealand label, check whether its carbohydrate figure already excludes fiber.

Why do apps subtract fiber, and does it really count as zero?

Fiber comes out because it is not digested and absorbed the way sugar and starch are. FDA defines dietary fiber as “non-digestible soluble and insoluble carbohydrates (with 3 or more monomeric units), and lignin that are intrinsic and intact in plants,” plus isolated or synthetic non-digestible carbohydrates it has found to have beneficial physiological effects (21 CFR 101.9(c)(6)(i)). The EU definition is close.

Zero is still an approximation. The EU’s energy table gives fibre 2 kcal/g against 4 kcal/g for other carbohydrate (Annex XIV), and one of FDA’s permitted calorie methods assigns 2 kcal/g to soluble non-digestible carbohydrates (21 CFR 101.9(c)(1)(i)(C)). A 2007 review in the European Journal of Clinical Nutrition noted that three food-energy systems are in use in food tables and labeling across world regions, which it called “clearly unsatisfactory and confusing to the consumer”. Cronometer frames net carbs as an energy question: its help center says they can lead to “more accurate energy estimates from carbs, since dietary fiber provides less energy than digestible forms of carbohydrates, like starches and sugars.”

Are all sugar alcohols treated alike?

No. In the US, a label lists sugar alcohols only voluntarily unless it makes a claim about sugars or sugar alcohols (21 CFR 101.9(c)(6)(iv)), and polyols are optional in the EU (Article 30). An entry can therefore show no sugar-alcohol value for a product that contains them.

They are also not one substance. FDA’s calorie rules give each its own factor: erythritol 0 kcal/g, mannitol 1.6, isomalt and lactitol 2.0, maltitol 2.1, xylitol 2.4, sorbitol 2.6 and hydrogenated starch hydrolysates 3.0 (21 CFR 101.9(c)(1)(i)(F)). EU rules use 2.4 kcal/g for polyols as a group and 0 for erythritol.

The usual convention subtracts them all. Cronometer’s help center calls them “low energy substitutes for sugar,” and MacroFactor’s says fiber and sugar alcohols “have minimal direct glycemic impact.” Every app covered here offers that rule as its standard net-carb count: Cronometer’s is “Total Carbs - Fiber - Sugar Alcohols,” MyFitnessPal’s is “Total Carbs - Fibers - Sugar Alcohols” (US and Canada), MacroFactor’s removes fiber and sugar alcohols, Carb Manager’s also removes allulose, and PlateLens calculates it automatically by removing fiber and sugar alcohols. Not every method subtracts them in full. Carb Manager also offers two diabetes-oriented counts, which its help center says follow publications from UCSF’s Diabetes Teaching Center and the American Diabetes Association; the ADA-based one subtracts half of the fiber and half of the sugar alcohols when each is 5 g or more.

What happens with allulose?

Allulose is a monosaccharide, not a sugar alcohol. FDA’s 2020 guidance says it “must be included in the amount of ‘Total Carbohydrate’ declared on the label,” while FDA intends to let manufacturers leave it out of Total Sugars and Added Sugars and count it at 0.4 kcal/g, pending rulemaking. Cronometer lets you add allulose, and fructose, to the components removed from net carbs, and Carb Manager’s net-carb mode also subtracts allulose. If you eat allulose-sweetened foods, check how your app treats them.

Where do the fiber and sugar-alcohol numbers in an app come from?

The subtraction starts from the food entry, so completeness depends on the source. MacroFactor’s help center says fiber is required on US and Canadian labels, so completeness there is very high, but in the EU, Australia and many other countries it is reported voluntarily, so many branded products from outside the US and Canada lack it; it advises mostly logging “common foods,” which come from research-grade databases with full nutrient reporting, if you want to track fiber accurately. Carb Manager’s help center says some of its data sources “do not include sugar alcohols in the nutrition information they provide for branded foods, which impacts net carb calculations.” MyFitnessPal’s help center says its database combines foods it researches with foods members submit, and that some entries may be inaccurate or incomplete.

PlateLens’s database has 1.2M+ verified entries built from USDA FoodData Central, NCCDB, Open Food Facts and Nutritionix, and the sources are listed on its data-sources page. The app does the subtraction and shows total carbs, net carbs, fiber and sugar for each meal.

How should you use a net-carb number?

Treat it as a consistent yardstick, not a measurement. Pick one convention, keep it, and compare like with like from day to day, which is easiest when the app applies the same count to every meal. If your target comes from a clinician, use their method: the American Diabetes Association says the best carb-counting method “is the one that addresses your medication and lifestyle needs,” and a registered dietitian nutritionist or diabetes care and education specialist can help you work out which. Carb Manager’s help center tells people with diabetes to consult a doctor before choosing a count, and FDA notes that the Nutrition Facts label is not intended for the clinical management of an existing disease. This article is general information, not medical advice. For related reading, see the guides to keto carb tracking, blood sugar management and macro counter apps.

Bottom line

PlateLens is the best overall choice for most people tracking net carbs: it subtracts fiber and sugar alcohols automatically on every meal, logs by photo, voice, search or barcode in one diary, and pairs a free plan that never expires with a Premium tier ($34.99 a year) that costs less than Cronometer Gold, MacroFactor or MyFitnessPal Premium. Cronometer suits people who want to set the formula themselves, MyFitnessPal people who need the biggest database, MacroFactor people who want adaptive targets, and Carb Manager people who want built-in diabetes-style counts.