It might actually be simpler in the UK - nobody describes themselves as working class anymore and there are very real upper class people so everyone from the PM down is middle class.
http://blogs.wsj.com/iainmartin/2010/08/10/how-middle-class-...
NB I like that quiz - if you enjoy drinking to excess and fighting you are working class or upper class but definitely not middle class (by UK standards).
Edit: I guess another way of defining "middle class" by UK standards is "someone worried about social status" - traditionally neither the upper classes or the working classes cared about social status.
destitute - checks discarded transit cards for remaining balances
poor - buys monthly transit passes
lower - buys used car with predatory/dealer "pay here" financing
lower-middle - buys used car with bank/CU financing
upper-middle - buys used car with cash, or new car with bank/CU financing
upper - buys new car with cash
rich - drives company car leased by an owned business, but uses taxis and Ubers in the city
ultra-rich - never drives; has on-call professional driver/pilot employeesTo me upper class means the literally Queen, or at least something like her cousin's son's uncle or something like that.
If you don't own a country estate or have any staff then you aren't upper class.
I wouldn't call the Queen or Prince "upper class", I'd call them the nobility. You still have remnants of an actual feudal class system whereas we do not. Our classes go solely by income. Roughly speaking, the lowest 25% is poor, anything between 25-90% is middle class (a term which has expanded over the years), 90-99% is upper middle class, and the top 1% is upper class. Of course there is no hard and fast agreement on it, and others will disagree about the exact demarcation lines on those ranges, but it's the same gist.
So I personally wouldn't call a nurse and a teacher upper class, but they could easily be upper middle class.
As an American I wouldn't call the queen upper class, I'd call her nobility or royality, a different class altogether and not really compatible to the American "class system" (so to speak).
American super rich have their own category too, I should have mentioned. Don't think there's a real concrete word for them but they are called stuff like "trust fund baby"(if they are rich because their parents are and don't have to work), the 1%, millionaires, and the super rich. There is a growing divide between the rich and the super rich in the US in the last several decades, which plays into it.
What I don't understand is why you'd turn class into a proxy for personal wealth, there are already lots of ways to refer to that - wages, household income, net worth - whereas class [in the UK] is a far more nuanced measure of ancestry, culture, occupation and attitudes to all of those things.
The US has a very "anyone can get rich" kind of cultural ethos so it makes sense our definitions would be very different.
There's also a distinction between upper class and the "frigging filthy rich" (salary in the millions) in the US. Lately they've been called "the 1%."
[Answer is probably "language isn't logical" but I'd settle for your reason not to use the more informative approach.]
How they obtain the money (education, job) or how they spend it (house, holiday) is not important by definition - however there is some social expectations of the American middle class.
Many Americans don't have the time off work for two holidays a year, even if they have plenty of money, which is another difference, which changes the American social expectations of the US "middle class."
A family with nurse and a teacher for example (two professionals) would bring in somewhere around $100,000/yr and be upper class.
There's a lot of variations by geography (cost of living) and stuff too, but I simplified it.
In reality the amount of financial security a family has is often a function of how well they manage it (as long as you are making above a certain amount where it becomes possible for financial security). If the above mentioned family over spent on a big house, two cars, a motorcycle, and other luxuries they consider normal, or even needed, then they can surely feel like they are living without much financial security, which doesn't "feel" upper class.
Unfortunately, middle class is a totally useless term because almost everyone describes themselves as middle class, I guess because they are somewhat out of touch with their spending and don't feel rich (previously mentioned family) or they are towards the bottom they don't want to feel poor. People who have a household income of $200,000 describe themselves as middle class. One of my coworkers, with a straight face, described me as middle class. I couldn't believe it - with a household income more than 3x the median household income in the US I can't with a straight face say I am middle class.
That's why politicians pander to "the middle class," because the majority of Americans identify with the middle class - even poor ones who don't consider themselves middle class but feel they will be there soon.
On the other side of the coin I have a friend who makes a middle class income, spends lavishly on consumer goods, and is always complaining about how poor she is.
Like I said, totally useless term.