how do i know if the calories are right

I noticed that there are different foods with a few differences between them in the database. So what I do is I look everything up individually, if possible I then look at the actual packaging to get an idea about how much it is per serving, and search for something similar - erring on the side of caution by overestimating if necessary. So for example, for a generic potato salad there are different entries and vary a lot in calories - I look at my packaging and then estimate how much I ate (or measure) and try to get closer to it - if potatoes are peeled, non peeled, if cucumbers are raw, chopped, eggs boiled, scrambled etc. and just save that and you can reuse it.

Basically, I do a bit of a research in the database to make sure I find the closest thing - doing it individually per item and then save them in the foods to be re-used.