Young people should be saving a lot more than their parents and grandparents. There are a lot of reasons for this, including lower expected investment returns. This article argues that the pattern of contributions make over their lifetimes mean they should be contributing at least 20% of their earnings most of their careers.
So during that last 10 years of our careers, what would we need to add to our 401(k) accounts each year in the example above to average 12% for our entire 40-year career? More than you might think — 24% per year. Given that the average employer matching contribution is 3%, that means that our contribution rate for the last 10 years of our careers would need to be 21%.