The vast majority of Americans may face one terrifying discovery at some point in their lifetimes: They haven't saved enough money for retirement. There are a lot of reasons why, but the three that our Fool contributors will discuss here are among the biggest.

Selena Maranjian 
One key reason that many Americans are not saving enough for retirement is that they're not saving at all -- they're putting it off. According to the 2014 Retirement Confidence Survey published annually by the Employee Benefit Research Institute, only 57% of American workers (or their spouses) were saving for retirement in 2014, down from a recent peak of 65% in 2009. Fully 73% have no retirement plan, and 36% have socked away less than $1,000. Yikes.

The more you put off devising a retirement plan and beginning to save and invest money, the more challenging your retirement is likely to be. One reason procrastination is so bad is that the earliest dollars you invest are the most powerful ones, as they have longest to grow. Check out the following table. It reflects how a one-time $10,000 investment grows over time at the stock market's long-term average annual rate of about 10%. Notice that in the early years, each year adds just a little more, while later years each add a lot. And all this is without any additional contributions. (Ideally, you'll be socking away a lot each year, and the differences from year to year will be even bigger.)


You'll Have...

5 years


6 years


10 years


11 years


20 years


21 years


22 years


23 years


24 years


25 years


30 years


31 years


Imagine putting off saving for retirement by only one year, and having your money able to grow for just 30 years instead of 31 before you retire. In the preceding example, your nest egg would be more than $17,000 poorer. Between year 10 and year 11, the difference is only about $2,600 -- showing how much later years matter. Procrastination is very costly when it comes to your financial security.

Dan Caplinger 
Most people agree that Americans don't save enough for retirement, and when you consider all the competing financial priorities in people's lives, it's easy to understand why. Young people entering the workforce now generally have thousands or even tens of thousands of dollars in student loans to pay off, sapping large amounts of disposable income that would otherwise be available for investment. Even for those who are fortunate enough not to have debt or get out of it quickly, more immediate needs such as buying a home, purchasing a vehicle, or paying the many expenses of having a family often force thinking about retirement to the back burner.

One way to encourage people to save toward retirement earlier is to point to the consequences of not doing so. The growing "sandwich generation" of middle-aged workers who are supporting both retired parents who didn't save enough for their golden years and their own children understand all too well what happens when people have insufficient retirement savings. Especially when it comes to paying for children's education, it can be tempting to put off saving for retirement to help your kids avoid having to go into debt. But if your children end up having to care for you after you can no longer work, the resulting burden can be far greater than having some student debt. Boosting your retirement savings will do your family a favor in the long run.

Keith Speights
While many Americans know they should save for retirement but aren't doing so, there are some who don't fully realize how important it is. These individuals aren't really procrastinating or focused on near-term financial priorities, as Selena and Dan discussed. They simply don't grasp how critical it is for their financial futures to have a regular savings program in place.

Three dollar figures underscore just how important retirement savings should be. First is the median household income for Americans nearing retirement (aged 55 to 64) -- $57,538 in 2013. The second figure is $15,528. That's the average annual Social Security benefit for retired workers. Our last number is $12,000 -- the median retirement account balance for near-retirement households, according to the National Institute on Retirement Security.

If we do the math, these figures tell us that the average American nearing retirement will need another $42,000 or so each year to maintain the same income level as he or she did before retirement. Sure, many retirees live off less -- perhaps 70%-80% of their pre-retirement income. But where will that additional money come from with only $12,000 saved? Too many Americans don't understand the importance of saving for retirement enough to understand the dilemma they could face.