Anyone who has taken the time to fill out the input required for more than one retirement calculator will know the output results vary dramatically. Recent studies by financial and academic institutions, in fact, show that the numbers you get could vary by 60 percent or more!
No matter how much careful skepticism you apply, there is no way you can use those calculators to help you reliably plan for retirement. As I wrote in a blog post earlier this year, such calculators fail to account for several factors while determining the “magic number” you seek. In fact, calculators don’t even give you a reliable range of numbers to choose from.
The problem with calculators
Not only do calculators each use different algorithms and assumptions, they also often leave important factors, like taxes or late-in-retirement expenses, out of the equation. Also, if one calculator assumes your return on investment will be 5%, and another predicts 7%, the results will be impossible to compare. More