Ignorance is bliss for some of your clients, a new retirement study says.

That’s because many individual investors think their retirement savings plans are on track, but often aren’t.

Some are overly optimistic about achieving retirement saving goals, says a big money manager that believes many retirement plan assumptions are flawed.

Natixis Investment Managers, in a new survey on retirement attitudes called “Retirement Reality Check,” reports that many respondents of all ages are underestimating their retirement costs.

The idea of a secure retirement is “a pipe dream for many hardworking Americans who need saving, beginning with a check of the assumptions behind retirement planning,” according to Ed Farrington, executive vice president of retirement savings strategies at Natixis.

That’s because they are miscalculating when they can stop working and live on their assets for the rest of their lives, the study said.

“A majority of American workers believe they will be comfortable in retirement—even if they have to be careful with their spending,” the study says. “But a deeper look at the attitudes and behaviors that can determine retirement security reveals this may be an overly optimistic outlook for many.”

Participants complained that “mounting debt and living expenses are top reasons Americans say they aren’t saving more for retirement.”

In conducting the survey, Natixis interviewed some 1,000 people of almost all ages who were eligible to contribute to a defined contribution plan.

“People are underestimating how much they need to save, but they may also be underestimating how long they need to save,” said David Goodsell, executive director of the Natixis Center for Investor Insight, in an interview with Financial Advisor.

Anthony Ogorek, a CFP in Buffalo, N.Y., says it’s his job to make people pay attention to the unique problems of retirement savings.

“You have to be realistic with clients and sometimes just tell them that they are going to have to work longer,” says Ogorek.

The Natixis study found the problem of retirement funding goes across generations.

For instance, the survey estimates that Gen Xers, aged 39 to 54, are missing chances to save more and be able to comfortably retire at age 61. Baby boomers, aged 55 to 73, are also not saving as much as they require to reach their goals, the survey said; they are older, so boomers need to save an average of $142,000 a year.

Millennials, aged 23 to 38, also are underestimating what they will need to put aside for retirement.

The good news is that all the groups seem to understand that they must consistently save to achieve their retirement goals.

How did boomers fall behind?

Boomers told the Natixis researchers that the most common reasons for lagging are that they should have started saving sooner, they contributed too little to their retirement plan and they needed more education earlier on saving for retirement.

However, the study also found some good trends.

Millennials, for example, are starting early to save for retirement. They are putting money in retirement plans on average at age 25. Still, the average millennial has saved only about 10 percent of his or her retirement saving needs.

“But the math takes a turn for the worse when they reveal an average retirement goal of only $822,789,” the study says. That problem is compounded by their belief that they will retire by age 61, on average. Goodsell says the $822,789 number is too low.

“For instance, baby boomers think they need $1 million, and that price is not going to go down over time.” He says millennials need to save about 19 percent more a year.

He says millennials’ retirement plans are flawed because they are saying they will retire “well before their Social Security age.” Goodsell notes that, in the first retirement years without Social Security, private savings “will be eroded much quicker.”

He also says age 61 is not realistic—that millennials will probably need seven or eight more years to contribute to their retirement funds and let them compound longer.

If not, “that may mean a generation, with the potential to live to age 100, could run out of money early on in a retirement that could last 30 to 40 years,” the study warns.

Generation Xers, sandwiched between those two generations, have unique problems, the survey said. Nonetheless, they still aren’t figuring on saving enough: They estimate they will need some $980,000 to retire, and that won’t be sufficient, according to Natixis.

Their current savings are not in line with their assumptions of retiring at age 64, Goodsell says.

“Currently, they have accumulated an average of just $166,328 in retirement savings. The leading edge of this generation has a little over 20 years until retirement, leaving plenty of time to potentially catch up, but many struggle to make the numbers work.”

One way financial pros say these people can close the gap is to use the catch-up provisions of many qualified plans. Here’s where an advisor could make a big difference, Goodsell says—by educating plan participants. Only 30 percent of Generation Xers take advantage of this provision allowing more saving, according to the study.

What keeps these middle-aged people from saving more and getting on track for a secure retirement?

“Generation X workers report that the biggest deterrent to plan participation is, “I have too much debt to pay,” the Natixis report says.

Goodsell says advisors should tell Generation Xers that using the catch-up provision “is one of the simple things you can do to make your retirement plan work.”

Boomers, a quarter of whom have begun taking retirement fund withdrawals, also have shortfalls.

But unlike younger workers, boomers believe it will take more savings to retire, about $1 million, the study says. Yet like younger workers, they underestimate what it will cost.

The study said boomers realize that late in their careers “they’ll have to work at least two years past the standard Social Security age of 67.”

Even if they are realistic about these critical considerations, “many miss on the other side of the equation,” the report said. “They need seven-figure savings to fund retirement, but a few short years out from retirement age, they’ve only saved 30 percent of their goal.”

Still, about half of boomers say they will be comfortable in retirement “if they watch their spending.” But 22 percent said they are struggling in retirement and “10 percent said they will never be able to retire,” according to the study.

What should boomers do?

To achieve a secure retirement, the average baby boomer needs to work a few extra years and save $142,357 annually until age 69, Goodsell says.

Generation Xers have a similar kind of golden years worry. Only about one in five said he or she was saving enough for retirement “to lead the life they desire,” according to the study.

And about a quarter of them told the survey they “don’t think they’ll ever be able to retire.”

The problem with all the age groups, Ogorek says, is that retirement planning can be very difficult.

“There are some factors you can control, such as saving more and spending less, but there are some factors you can’t control, such as losing a job or whether a loved one has a health issue,” he says.

Goodsell agrees and says there are many variables that can ruin a plan, such as higher costs, including higher-than-expected inflation rates, or lower-than-expected rates of returns on investment.

An example of the latter would be if your client retired in conditions similar to the stagflation of the 1970s. That was a decade of poor equity returns and periods of double-digit inflation.

These unpredictable factors, Goodsell argues, mean retirement planning should always be biased on the side of bigger-than-needed retirement assets.

“It is a lot less painful,” he says, “to overestimate what you need than to underestimate it.”

Some Highlights of the Natixis Retirement Savings Study