Social Security will be the primary means of support for millions of workers after they retire. But do you know as much as you ought to about the benefits that middle-class Americans get from Social Security?

In the following video, Dan Caplinger, The Motley Fool's director of investment planning, goes through a typical situation for middle-class workers. Using Social Security's benefits calculator, he notes that a 62-year-old worker making $50,000 a year can expect to replace between a quarter and a half of his pre-tax earnings from Social Security benefits, depending on when he starts taking benefits. But as Dan notes, it's essential to be smart about when to take benefits, as the decision really does make a big difference in your financial prospects overall.