How do you determine your seniority?

I'm looking through some companies careers pages and most of them are looking for senior software engineers. But when I look at the requirements, the want 2-3+ years of experience. Personally I don't feel that 2 years is enough to be senior, more like experienced junior-middle

Check how many gray hairs you have, divide by how many years you’ve been writing code.

I've updated the description :)

So they want someone senior with 2-3 years of experience being senior. So that’s a total of 5-7 years working full time.