If retirement readiness were a college class, the U.S. would be shrugging and using the old adage "Cs get degrees."

That's because Fidelity gave Americans a C grade - 76 percent - in its latest biennial retirement assessment study. The score is up from 2013, 69 percent, but still means "you're falling short of completely covering estimated retirement expenses," Ashlea Ebeling wrote for Forbes.

The bottom line: Americans "better get on track" or risk sacrificing the pleasantries of retirement, according to Forbes.

According to ThinkAdvisor, Fidelity's Strategic Advisers conducted the study with data through an August survey of 4,650 working households. These households brought in at least $20,000 annually, and respondents were aged 25 to 75.

The data indicated all interviewed expected to retire eventually.

Forbes noted the other positive news.

"The good news is that 45 percent of households are in the green zone: 27 percent of households score at 95 or above, meaning they are on track to cover nearly all retirement expenses; and 18 percent of households score between 80 and 95, meaning they are in good shape, on track to cover essential expenses but not discretionary expenses like travel and entertainment," the report read.

However, Paul Katzeff wrote for Investor's Business Daily that 55 percent of people aren't on pace to live how they wish post-work.

John Sweeney, Fidelity executive vice president for retirement and investing strategies, cited steps these Americans can take to improve their chances of a comfy retirement.

First, people should strive to save 15 percent of their income yearly, according to IBD.

"Time has the biggest impact on reaching readiness," IBD quoted Sweeney as saying.

Mary Beth Franklin detailed for InvestmentNews Sweeney's other two tips: reviewing asset allocations and working longer if needed.

According to InvestmentNews, the effectiveness of these measures depends on the time people have left until retirement.

"It is easier to convince a 20-something to live on 85 cents of every dollar they earn right from the beginning," InvestmentNews quoted Sweeney as saying. "It is harder for more established workers, but we urge them to bank their bonuses or raises rather than succumb to lifestyle creep."

InvestmentNews' piece indicated Fidelity has a personalized retirement tool to assist people in figuring how prepared for retirement they are.