For a detailed breakdown of how Dogen arrived at each of these numbers, read the full post on Financial Samurai.

In this example, the couple contributes to their 401(k) plans — although they don't max them out — and are working on paying down credit card debt. But even though they qualify as "upper class," after taxes, fixed costs, childcare and discretionary expenses, there's only $5,700 left each year to go towards other savings goals, investment accounts or retirement funds.

They're rich by many standards and yet they appear to be just getting by.

This deficit highlights a crucial lesson: Thanks often to lifestyle inflation, as well as the high cost of certain necessities, earning a higher salary doesn't always translate to financial peace of mind — or to a well-padded savings account.