The site has the calculator to do what you and I can't do "in our spare time at home" - figure the odds of going broke in retirement. Let's start from the wisdom financial planner William Bengen introduced 20 years ago. The first is to follow the required minimum distributions dictated by the Internal Revenue Service. Why? Because there are several other safety valves on future spending: Using the Vanguard longevity tool, for instance, there is only an 18 percent chance that either person in a 65-year-old couple will live 30 years. For most people, the declines in regular consumption are greater than the increases in medical spending. Many older couples happily reduce their shelter spending as part of a retirement plan or as part of widowhood. In my Dec.