It's a very interesting topic and it is very hard to tell.
Both the Human Development Index measures, and another report that now I cannot quote as I don't remember its name, show that the lowest income pentile in the US has a more or less equivalent Human Deveopment Index as the middle (or third) pentile in Hungary. Including the access to food, money, education, healthcare, sanitation, free-time, etc...
So I don't know how to compare our standards and that in the US.
Also, I read that the definition of "middle-class" today is that the individual or household members will have 1/3 of their monthly income remained after paying for housing and basic food.
Well, I earn way above the average in Hungary, live alone and I don't have 1/3 of my income left after housing and paying for food.
At the same time my job needs BSC degree, at least two foreign languages fluently, and the salary is much above average within the country.
So it is hard to judge. It would be good to know the categories better.
As far as what I saw in Germany, Sweden, UK,
My lifestyle and fiscal possibilities might be: lower-middle class. Although my education is better than that and my interests as well as my job, are very different from that of the working-class or lower-middle class of Western Europe. That would rather be middle-class.
Within Hungary I am at least middle-class.