A majority of the more than 1,100 owners of small businesses have significant concerns about their own retirement, according to study by The American College.

In that study, more than 1 out of every 3 women and 1 out of every 4 men said they had not yet made estimates of how much money they will need in retirement.

“The lack of retirement planning by so many people is stunning, especially since business owners have no one else to rely on when it comes to putting their retirement plans in place,” Mary Quist-Newins, director of the State Farm Center of Women and Financial Services at The American College said. “When you consider that the mean age of our respondents is just over 50, you have to wonder . . . Small business owners need to start preparing for retirement now.”

Other information from the study indicates that more than two thirds of both men and women had developed an estimate for their needs in retirement, but less than half of those business owners had done so with the help of an expert. Also, 25 percent said the estimates they made came with the help of online calculators.

However, online calculators can be tricky because difficult to be certain that issues such as inflation, future taxes and medical expenses are being accurately taken into account. While many people in the survey had taken the time to at least consult an online calculator, more nearly 8 out of 10 said they had no written plan for their retirement.

The survey results suggest that millions of Americans are not adequately prepared for retirement. That’s based on figures from the U.S. Small Business Administration.

The survey was conducted online in the U.S. by Ipsos on behalf of The American College and relied on 1,255 interviews of people who identified themselves as business owners. The definition used was a person with at least 50 percent ownership, and a say in the financial and business decisions, of a small company. The businesses in the survey all had been in operation for at least three years and had yearly revenues exceeding $50,000.

The American College is a non-profit education institution devoted to financial services.