Few Americans know how much they pay in fees for their 401(k) plan and many aren’t even aware they pay any fees, according to a new survey from TD Ameritrade. Of the 1,000 investors surveyed, only 27% knew how much they were paying in 401(k) fees and 37% thought they paid no fees at all.

The reality is far different, of course. The plans have administrative fees, investment fees for the mutual funds a participant chooses and fees for optional services such as loans — which can all affect the performance of retirement assets — and plan sponsors are required to disclose all regular expenses and fees to plan participants on a quarterly basis. Unfortunately, most people don’t read those reports.

“It can be onerous to read through all the disclosure information and documentation to understand the fees, but just because it’s hard to decipher doesn’t mean those fees don’t exist,” said Matthew Sadowsky, director of retirement and annuities at TD Ameritrade.

(Related: Workers Regret Not Saving More for Retirement: Study)

With that in mind, TD Ameritrade launched a free 401(k) fee analyzer tool powered by FeeX that is available to all self-directed investors. The tool provides an analysis of the fees participants pay for their defined contribution plans, including administrative fees and individual fees for the mutual funds they own in their plan.

“To have all-in costs at your fingertips online is a big deal,” says Knut Rostad,” president of the Institute for the Fiduciary Standard.

(Related: 3 Ways to Improve Retirement Plan Returns)

While individual investors don’t have much say in the administrative fees of their plans, which fall under the jurisdiction of plan sponsors, they do choose the funds they invest in and, when they leave an employer, they decide whether to maintain their savings in the 401(k) plan or roll them over into an IRA or a 401(k) plan at their new employer. The TD Ameritrade fund analyzer tool lets investors compare the costs among these choices.

“The common belief is that all 401(k) funds have institutional pricing that’s cheaper than those available to individual investors, which is not always the case,” according to the TD Ameritrade announcement. “Oftentimes, similar securities with comparable holdings can be found in the public markets at a lower fee … And, if more than one 401(k) is involved, consolidating multiple accounts into a single IRA can make it easier to monitor and manage progress toward retirement goals.”

Nearly one-third of Americans roll their old 401(k) account into a new employer’s plan, slightly more than one-third choose a rollover IRA, and 22% keep the funds with the original employer. In addition, 13% cash out their plan when leaving a job, which can result in tax penalties, depending on the age of the plan participant, and will reduce the individual’s retirement savings.

— Check out TD Ameritrade Extends Trading Hours for Some ETFs on ThinkAdvisor.