How much should you really set aside for retirement?

It's true that many Americans are ill-prepared for retirement, but the situation isn't as dire as some may think.

About half of U.S. workers are actually on track to retire comfortably, according to research from the Center for Retirement Research at Boston College. What are they doing right?

The center estimates that in order to maintain their lifestyle in retirement, households need about 70 percent of preretirement income on average. Under current law, Social Security can replace about 36 percent of their final inflation-adjusted earnings. In order to make up the difference, it estimates savers need to set aside about 15 percent of their pay over the course of 30 years to retire comfortably.

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Those with a longer time horizon—such as those who start saving in their 20scan begin by saving 10 percent of their pay annually and gradually increase the percentage over time.

Of course, many Americans haven't been consistently saving even that much. A Bankrate survey, released this week, found that 46 percent of Americans are putting less than 5 percent of their annual incomes into longer-term savings. Although it did find that almost a quarter of the population is saving more than 10 percent of their income.

For those playing catch-up, it can be tough to determine how much more to set aside. But the Center for Retirement Research report offers some guidelines. It estimates that those who start saving at 45 and hope to retire at 65 will need to save 27 percent of their income each year. That drops to 10 percent, though, if they can put off retirement until they're 70 years old.

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For those who are starting even later, the report recommends they "work longer and cut current and future consumption in order to reduce the required saving rate to a more feasible level."

Fidelity, the nation's largest retirement plan provider, also offers some general benchmarks to help savers make sure they're on track.

By age 35, it recommends you have the equivalent of your income in savings. By age 45, aim to have your savings equate to at least three times your current salary. And by the time you're in your last years of employment, your savings should be at least eight times your final salary, according to Fidelity.

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Your life, of course, may not fit precisely into this formula. But saving early and making additional contributions when you can will give you more options later. You can always work longer in a different capacity or retire a little later. "It's important to consider your particular situation, and adjust accordingly," said Fidelity Executive Vice President John Sweeney.

Set a retirement savings goal, make regular contributions to your retirement accounts, and make adjustments where you need to in order to stay on track and you'll be on your way to retiring well.