If you think you're in the dark about retirement, you're not alone. A good 81% of Americans have no idea how much money they'll need to fund their golden years, while countless members of the workforce have yet to start saving in the first place. If you'd have a hard time calling yourself retirement-savvy, here are a few key things to be aware of.

1. You can save without a 401(k)

Despite the fact that it's one of the most popular retirement savings tools out there, only 79% of the workforce gets the option to participate in a 401(k). But even if your employer doesn't offer a sponsored retirement plan, you can still save for the future with an IRA.

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The one drawback of going this route is that the annual contribution limits for traditional and Roth IRAs are $5,500 a year for workers under 50, and $6,500 a year for those 50 and over. These thresholds are considerably lower than what 401(k)s allow for -- $18,000 a year for workers under 50, and an even more generous $24,000 for those 50 and above. But if you start maxing out an IRA early on in your career, you'll still amass a nice, respectable sum. Case in point: Contributing $5,500 annually over 30 years will leave you with an ending balance of $435,000 if your investments bring in an average yearly 6% return, which is well below the stock market's average.

2. You can't live on Social Security alone

Despite the fact that many seniors today rely heavily on Social Security to pay their bills, the program was never designed to sustain retirees. Rather, it was meant to supplement whatever additional income sources they have, be it a pension, 401(k), or earnings from a part-time job.

If you're planning to live off Social Security without independent savings, here's a wake-up call for you: The average recipient today collects just $1,360 a month, or $16,320 a year, in benefits. Now, if that sounds like enough money to you, then by all means, neglect your savings. Otherwise, you'd be smart to start setting part of each paycheck aside for the future.

3. Healthcare will cost you a bundle

The older you get, the more health issues you're likely to encounter, and if you're not careful, the costs involved might throw you for a serious loop. Though you will be eligible for Medicare once you turn 65, it won't cover all of your expenses. Furthermore, while Medicare Part A, which covers hospital visits, is free for most enrollees, you'll pay a premium to participate in Medicare's other parts, like Part B, which covers diagnostic services, and Part D, which covers prescription drugs.

So just how much money are you looking at spending on healthcare costs in retirement? According to recent projections, a healthy 65-year-old couple today will plunk down a whopping $400,000 on medical care throughout retirement. If you're not healthy, there's a good chance that figure will rise. The more you save and prepare for what could end up being your single greatest retirement expense, the less stress you'll have as a senior.

4. You may end up living longer than you think

An estimated 40% of Americans think they'll only need enough retirement savings to cover a 12- to 17-year span. But if you're planning on retiring at what the Social Security Administration considers full retirement age -- which is either 66, 67, or 66 and change -- then there's a good chance you'll need your savings to last much longer.

According to the Social Security Administration, the average 65-year-old man today is expected to live until 84.3, while the average 65-year-old woman is expected to live until 86.6. But a quarter of seniors are expected to live past 90, which means that if you retire at 67 but live until 91, you'll have 24 years' worth of expenses to cover.

Furthermore, one out of every 10 seniors is expected to live past age 95, and if that ends up being the case for you, you'll need an even more substantial nest egg. The same holds true if your plan is to retire in your early 60s. That's why when it comes to estimating your life expectancy, you're better off erring on the side of optimism, and saving accordingly.

You don't need to be a financial expert to get a good handle on retirement. What you really need to do is read up on the costs you'll most likely encounter as a senior and start saving for them as early on in your career as possible. This way, you'll be better prepared for whatever eventually lies ahead.

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