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 break down some of the mutual funds with the top Zacks Mutual Fund Rank and the lowest fees.

JPMorgan Large Cap Growth R5 (JLGRX Quick QuoteJLGRX - Free Report) has a 0.53% expense ratio and 0.45% management fee. JLGRX is a Large Cap Growth mutual fund, and these funds invest in many large U.S. firms that are projected to grow at a faster rate than their large-cap peers. With yearly returns of 14.88% over the last five years, this fund clearly wins.

AMG Frontier Small Cap Growth I (MSSCX Quick QuoteMSSCX - Free Report) : 0.96% expense ratio and 0.7% management fee. MSSCX is a Small Cap Growth mutual fund building their portfolio around stocks with market caps under $2 billion and large growth opportunities. With yearly returns of 9.8% over the last five years, MSSCX is an effectively diversified fund with a long reputation of solidly positive performance.

Janus Henderson Enterprise I (JMGRX Quick QuoteJMGRX - Free Report) . Expense ratio: 0.77%. Management fee: 0.64%. Five year annual return: 9.21%. JMGRX 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.

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.