I came across this idiom and can understand from the dictionaries that it refers to X disregarding Y.
In my language using “nose’s length” would literally say: “one can see one’s nose’s length” or “one knows one’s nose’s length”, which means that one is aware of his/her own level, generally, or in a specific field, this having no relation or connotation of disregard but simply it’s about self awareness.
My question is if in English we can use “to look down one’s nose at oneself”. I think that even if it were used would mean that one shows disregard to oneself, which is not what I’m looking for.
Is there an equivalent idiom in English which shows the awareness of one's own level?