How much money do you need to retire one day?

If you're like most Americans, you have no idea.

In a new survey from Bankrate.com, 61 percent of respondents said they don't know how much money they'll need to save for retirement. In every age group surveyed, at least half were unsure of an amount.

"The key to retirement savings is to actually save for retirement. Put away at least 10 percent of your pay, including any employer contributions, into your retirement account and do it yesterday," said Bankrate analyst Taylor Tepper in a news release. "There are pretty sophisticated online calculators and tools that can help you estimate how much you're going to need, and you can always hire a fee-only certified financial planner if you want a little more hand holding."

In the survey, more than half of Americans said they've sought advice on their retirement planning.

Ken Kamen, president of Mercadien Asset Management in Hamilton, said most people don't know how much money they need to retire because they've never taken the time to consider the subject, likely because they're struggling to survive financially today and they're not excited to find out how much they'll need to survive financially down the road.

"There's not a one-size-fits-many solution for this problem," Kamen said. "It's a very individual issue that people need to think through if they want to have anything that even remotely resembles a realistic answer."

The first step of coming up with a dollar amount, he said, is having an understanding of what kind of life you'd want to have during retirement. The total tab is likely much different for a couple planning to take a couple trips each year versus those just looking to escape New Jersey and settle down elsewhere for some peace and quiet.

And the calculation shouldn't only include leisure and on-the-surface necessities such as housing and food, Kamen said.

"There are so many things that people don't figure in," Kamen said. "Medical expenses is one of them, insurance is another one, maintenance on the things they own — if a car breaks down or the furnace breaks down."

Among respondents who do have an estimate on retirement funding, the median amount came in at $650,000. Eight percent of respondents — mostly Gen Xers — said they'll likely need over $1 million to retire.