The tricky part can come when the amount of an ingredient in your recipe is not expressed in the same units as it is listed in your carbohydrate book. Here is a list of standard equivalents for the units of Imperial measuring. These can also be found in many cookbooks. It is useful to know this information in case the amount of an ingredient required in your recipe is not the amount listed in your carbohydrate book. Of course, if you cook with the Metric system, you will not need to use these.
Some recipes have obvious serving sizes.
For instance, if you are making chocolate chip cookies, the serving size is one cookie. In this case, you would bake the entire batch of dough, keeping track of how many cookies your kids swipe along the way. I'm sure you know by now that you never end up with the same number of cookies that the recipe says you will. The result is the number of carbs in one cookie. Just multiply by the appropriate number.