Millions of Americans rely on Social Security benefits to make ends meet in retirement. But given how complex the program is, many don't understand how to figure out how much money they'll get from Social Security.

In the following video from The Motley Fool's series on retirement investing, sponsored by TD Ameritrade, Fool consumer finance expert Dayana Yochim talks to Dan Caplinger, the Fool's director of investment planning, about figuring out your Social Security benefit. Dan notes that your base benefit amount is based on your 35 top-paying years, with the average adjusted for inflation serving as the starting point for the calculation. Then, the Social Security Administration puts that average into a formula, paying $0.90 per $1 of earnings up to a certain amount based on your retirement date, and then $0.32 and $0.15 per $1 of earnings at two break points above that amount. But Dan points out that you can get bigger or smaller benefits than that depending on whether you take Social Security earlier than or later than your full retirement age. Still, it's critical to know your base benefit amount so you can make smart decisions about your personal Social Security strategy.