This article provide two really good charts.  The first chart covers what investing $5K, $10K, or $15K annually over five year increments will accrue an investor when returning 8%.  Off course, the earlier you start, the better the results.  But, the real benefit of this chart is revealed when one estimates the annual income produced from this nest egg when using a 4% withdrawal rate.  Tellingly, the second chart shows that 20 years of saving $15,000 at 8% yields $29,000 in annual income in retirement, but start a mere 10 years earlier and that $15,000 at 8% for 30 years yields $72,000 in annual income (almost 2 and 1/2 times greater).  I believe the second chart helps to put in more concrete terms what a retiree can expect from their nest egg in retirement; notwithstanding, that a back of the envelope 4% withdrawal calculation will not work for every retiree's unique and particular circumstances.