The large majority of Americans are way behind on saving for retirement. Just by way of illustration, 21% of adults have a grand total of $0 saved for the future, and another 10% have set aside less than $5,000. Even looking to an older demographic that might be presumed to be better prepared, half of Americans in their 40s have less than $63,000 in retirement savings. Why aren't they more worried, you might wonder? Well, it's possible some of them have fallen into the trap of thinking Social Security will get the job done.

Best revisit that assumption, warns personal-finance writer Maurie Backman, whom Motley Fool Answers hosts Alison Southwick and Robert Brokamp tapped this week to dispel some retirement myths. For one, the government's retirement benefit is designed to keep you out of poverty, not to replace your prior paycheck.

A full transcript follows the video.

This video was recorded on Nov. 13, 2018.

Alison Southwick: The next myth. Social Security will cover the bills in retirement.

Maurie Backman: It won't. No, no.

Robert Brokamp: That's all you need to say. It won't!

Backman: Next! And it's not because Social Security is going away. Let's debunk that, too, while we're here for a second. Yes, there are talks of future benefits cuts if things continue to go the way they're going. Generally speaking, we will have Social Security down the line, but the thing that a lot of people need to realize is that those benefits are only designed to replace roughly 40% of the average earner's pre-retirement income.

And that means, first of all, that if you are a higher earner, that it will replace even less. So we just talked about the fact that as a rule of thumb, you want the 70%-80% replacement target. Social Security, then, if you were an average earner, will maybe cover half of that, so the other half is going to have to come from somewhere, whether it's your retirement savings in an IRA or a 401(k). Maybe you're lucky enough to have a pension. Maybe you're going to work. Maybe you're going to be a killer landlord and rent out different rooms in your house and take in income that way.

And that's all fine. It doesn't have to come from a single source, but I think the key is to be realistic about what Social Security will and won't pay for.

Brokamp: I mean, the average benefit this year is $17,000. So Social Security is basically poverty protection. It's just enough to keep you out of being homeless and without any food, but it's not enough to pay for the retirement that most people want.

Backman: Exactly.

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