CarbTable practical guides
Carbohydrates, sugars and fiber
The carbohydrate value used in this catalogue is USDA carbohydrate by difference. It includes dietary fiber; sugars and fiber are not extra amounts to add on top.
Read the total first
The large carbohydrate number in CarbTable is the total for the selected food and quantity. The smaller nutrient values describe other aspects of that same portion.
Why the components may not add up
Sugars and fiber do not describe every component of total carbohydrate. Analytical methods and rounding also affect the figures. CarbTable preserves the source values rather than forcing the displayed components to equal the total.
Total sugars are not added sugars
The sugars figure is total sugars reported by the source. It does not tell you how much sugar was added during preparation. A missing value is shown as a dash, not as zero.
Why we show total carbohydrate
This version displays total carbohydrate and dietary fiber separately. It does not estimate net carbs or adjust a result for medication decisions. Use the original record and your health professional’s guidance when individual interpretation is needed.
A worked example from the catalogue
For 100 g, Apple, with skin reports 13.8 g total carbohydrate, 10.4 g total sugars and 2.4 g fiber.
The sugars and fiber are already included in the carbohydrate figure. Adding all three would double-count those components. The calculator keeps them as separate readings for the same quantity.
Check the original USDA record. Values here come from the same catalogue records used in the calculators.
Check the source
This guide explains how to use the reference data. Read the USDA documentation and CarbTable’s methodology.
Prepared by CarbTable, October 26, 2026. Editorial policy and review status. General information, not individualized dietary or medical advice.