Politicians and economists tend to disagree about how to calculate middle class income. Financial Samurai calculates middle class income based on the individual level: +/- 50% of one's city's household income for one's age. Politicians, thinking about taxing the wealthy, are more liberal with their definitions of middle class income.
For example, in 2013, both presidential candidate Mitt Romney and President Obama defined middle class as those households making $250,000 a year or less. The standard definition of middle class income at the time was between $25,000 and 100,000 per year. In 2012, the median household income was $50,054. The median is calculated by putting numbers in value order and finding the middle number.
ABC news calculated the middle class by taking the income range between the 30th and 70th percentiles of income distribution in America, which is between $32,900 and $64,000 a year. This definition of middle class is much more conservative than those utilized by Obama or Romney.
Of course there are subgroups within the middle class range. They include the lowest end of the middle class spectrum, the working class. These people may have technical training, but few individuals in this category have college degrees, and they usually work for hourly wages. The lower-middle class typically include those people with college degrees, but they do not have the graduate degrees needed to bump them up into the upper-middle class. Those in the upper-middle class tend to have more comfortable living situations than others due to the extra income gained by obtaining graduate degrees and specialization in their respective field.