Reading labels is really important. I find my info online also

And weigh or measure to the "portion size" on the label

If something says it has 13 carbs that is only if you measure out 2/3 of a cup or whatever

Some count "total carbs" but many will count "net carbs"

Total Carbs (in grams) minus Total Fiber (in grams) minus Sugar Alcohols/Polyols (in grams) = Net Carbs

And those three things are listed on the nutrition label (but if there are no polyols they don't print it on the label as zero - like many vitamins/minerals, only there if they are in the product)

Simply look at the label also carb content lists can be found online. Atkins is a good source of information