How reliable is the perception of one's own intelligence?

There are people who believe themselves to be genuinely smart. There are also (fewer, in my opinion) people who consider themselves less intelligent than average.

Statistically, isn’t it highly improbable for everyone to be right in their perception?

You may also add how smart you think you are, if you’re up to others commenting ;)

For this question, I’m defining intelligence as stellar problem solving, quick reasoning, effortless gathering and applying of knowledge. I know there are many forms of intelligence, but I think there is a certain kind we all think of when hearing the word. If anyone has a proper definition, I’d be glad to hear it!