Nearly half of baby boomers have nothing at all saved for retirement, according to a report from the Insured Retirement Institute.

For those who are falling behind on their retirement savings (or have yet to begin saving at all), relying on Social Security benefits may be the only way to financially survive retirement. Even if you do have a solid nest egg, the extra money you receive from Social Security can make the difference between a comfortable retirement and a truly fantastic one.

But how much will you actually receive in Social Security benefits? The average check amounts to $1,461 per month, according to the Social Security Administration, but your exact number depends on a few factors. It's a good idea to determine what you can expect to receive before you retire, because that can have a major impact on how you build your savings.

Determining your estimated benefit amount

There's a fairly complex formula involved in calculating your benefits, but don't worry -- you won't need to run the calculations yourself (unless you want to, of course). Rather, the easiest way to get an estimate of your benefit amount is to check your Social Security statements online.

Through the my Social Security program, you can create an account and check your statements quickly and easily online. These statements report your earnings for the year, as well as the amount you're estimated to receive in Social Security benefits based on those earnings. It only takes a few minutes to see your estimated benefits, and yet only 43% of workers who have a my Social Security account have actually accessed their statements, according to the SSA.

Keep in mind that the amount you see on your statement may not be the exact amount you end up receiving because your exact benefit amount depends on a couple of factors.

First, your basic benefit amount is based on your 35 most profitable years of work. So if you haven't yet worked for 35 years, your benefit estimate won't be entirely accurate. This is especially true if your future earnings end up being much higher or lower than what you're earning now. Also, if you don't work for a full 35 years before you claim benefits, that could bring down your benefit amount because you'll have zeros in the calculation to account for the years you didn't have any income.

Another factor that impacts how much you'll actually receive is the age when you begin claiming benefits. Your basic benefit amount assumes you'll be claiming at your full retirement age (FRA), which is age 67 for those born in 1960 or later, and either 66 or 66 and a few months for those born before 1960. You can claim as early as age 62, but for every month you claim before your FRA, your benefits will be reduced. If you have an FRA of 67, your benefits will be reduced by 30% if you claim at 62.

On the other hand, you can also increase the amount you receive each month by waiting until after your FRA to claim. For each month you delay benefits past your FRA -- up until age 70 -- you'll receive a little bit extra each month. Those with an FRA of 67 can expect to receive an additional 24% on top of their full benefit amount by waiting to claim until age 70. So the estimated amount on your Social Security statement isn't set in stone, and if you claim earlier or later than your FRA, you'll receive more or less each month.

How your benefit estimate affects retirement planning

Knowing how much you're expected to receive in Social Security benefits does more than simply satisfy your curiosity; it can also help you more effectively plan for retirement.

Social Security benefits are designed to replace around 40% of your income in retirement. So while they shouldn't be your only source of retirement income, they can cushion your personal savings. As you're determining how much you need to save for retirement, don't forget to consider how your benefits will affect that number.

For example, say you expect to need around $50,000 per year in retirement, and you also anticipate receiving around $1,600 per month in Social Security benefits if you claim at your FRA. Those benefits amount to $19,200 per year, meaning that of the $50,000 you'll need each year, only around $30,800 will have to come from your personal savings. That can make it significantly easier to save, since you won't need to set aside as much per month in order to reach your retirement goal.

If you're still struggling to save for retirement, you may choose to delay claiming Social Security benefits by a few years to earn those bigger checks. In this example, say you'd be receiving close to $2,000 per month by waiting until age 70 to claim. That comes out to around $24,000 per year. If you still need $50,000 per year to get by, that means only $26,000 per year will need to come out of your own pocket, as opposed to $30,800 had you claimed benefits at your FRA. As an added bonus, if you also continue to work a few more years while you're waiting to claim benefits, that gives you more time to keep saving.

Social Security benefits can be incredibly valuable in retirement, particularly if your savings are falling short. But if you have no clue what monthly benefits you can expect to receive, that can make retirement planning a challenge. The more you know about how much you may receive and how those benefits impact your savings, though, the easier it will be to prepare for your best retirement life.