It is never too late to invest in mutual funds for retirement. As such, if you plan to invest in some of the best funds, the Zacks Mutual Fund Rank can provide you with valuable guidance.

How can you tell a good mutual fund from a bad one? It's pretty basic: if the fund is diversified, has low fees, and shows strong performance, it's a keeper. Of course, there's a wide range, but using the Zacks Mutual Fund Rank, we've found three mutual funds that would be great additions to any long-term retirement investors' portfolios.

Let's take a look at some of our top-ranked mutual funds with the lowest fees.

Bridgeway Omni Small Cap Value Fund (BOSVX Quick QuoteBOSVX - Free Report) : 0.88% expense ratio and 0.45% management fee. BOSVX is a Small Cap Value mutual fund, investing in small companies with stock market valuation less than $2 billion. With annual returns of 13.85% over the last five years, this fund is a winner.

JPMorgan Intrepid Value Fund C (JIVCX Quick QuoteJIVCX - Free Report) : 1.23% expense ratio and 0.3% management fee. JIVCX is a Large Cap Value mutual fund, which invests in stocks with a market cap of $10 billion of more, but whose share prices do not reflect their intrinsic value. With yearly returns of 10.98% over the last five years, JIVCX is an effectively diversified fund with a long reputation of solidly positive performance.

Principal Mid Cap J (PMBJX Quick QuotePMBJX - Free Report) is an attractive large-cap allocation. PMBJX is a Mid Cap Growth mutual fund. These funds aim to target companies with a market capitalization between $2 billion and $10 billion that are also expected to exhibit more extensive growth opportunities for investors than their peers. PMBJX has an expense ratio of 0.8%, management fee of 0.58%, and annual returns of 12.36% over the past five years.

There you have it. If your financial advisor had you put your money into any of our top-ranked funds, then they've got you covered. If not, you may need to talk.