It's a jokey bit of conventional wisdom that everyone thinks they're middle class. "Middle class" has come to mean something about what kind of values one has, and even weirder, one's value to the country. But, really, it has to do with how much money you make.
Memphis blogger Steve Ross has a good post in which he shares an actual fiscal definition of "middle class" and explains what that financial reality looks like.
While earners making up to $140,000/year may qualify as Upper Middle Class, its important to understand that they represent the top earners in the United States. Only 11% of earners make more than $150,000 and just over 5% of families in the US make more than $200,000.
$200,000+/year isn’t middle class. Its wealthy, even though it may not seem like it to the people making that kind of money.
In order to make policy that creates conditions where more people reach that threshold, we have to have our facts straight. Based on the discussions by both Presidential candidates over the past few weeks, we don’t have a realistic understanding of that yet.
I think that last point is the most important. But head over there for an actual numerical breakdown.