The standard psychological questionnaire for depression doctors have given me is the PHQ-9. It names a symptom, and for each symptom it gives four possible responses in severity. The responses are worth points, the points are totaled, and the final score is supposed to be indicative of how severe a person's depression is.

This is what it looks like:

According to Wikipedia, the final score indicates the following:

To be perfectly blunt, while I suppose this functions for doctors to get an idea of where their patient is at, it's absolute garbage for giving the patient a sense of how depressed they are. Knowing how many times in the last two weeks you’ve felt ‘down, depressed, and hopeless’ isn’t super helpful when you’re trying to understand - or worse, explain to someone else - what it's like in your head.