A simple savings tactic that can boost your nest egg

When should you retire
When should you retire?   

Many Americans may not save enough, but most admit they have the ability to save more.

A new survey finds half of American workers say they don't save—or don't save more—for retirement because of their cost of living and day-to-day expenses. As a result, nearly six in 10 (57 percent) have saved less than $25,000, according to the Employee Benefits Research Institute's 2015 Retirement Confidence Survey, released Tuesday. Yet, seven out of 10 workers surveyed admit they could put a little more money away, even if it's just $25 a week.

The EBRI survey, one of the most comprehensive annual reports about American's retirement savings, finds that over the last two years U.S. workers have grown more confident about their ability to have enough money to live comfortably in retirement. After falling to record lows between 2009 and 2013, retirement confidence has been on the rise. More than half of workers are "somewhat" or "very" confident they'll have enough money to retire. "But this is based on the increasing optimism of those who indicate they and/or their spouse have a retirement plan," say the report's authors.

Read MoreAt what age can you really retire?

Whether saving in an IRA, a defined contribution plan like a 401(k) or 403(b), or a defined benefit plan like a pension, having a retirement plan makes a huge difference, the survey found. Six out of 10 workers with no retirement plan had saved less than $1,000. Among the most aggressive savers with over $100,000 or more, 34 percent had a plan.

"Amazingly, only 48 percent of workers surveyed said they've taken the time to calculate the amount of money they'll need in retirement," according to Luke Vandermillen, vice president of retirement and investor services at Principal Financial Group. "Even a small contribution over the course of someone's career, even with a moderate rate of return, can provide a significant difference in the amount that you have accumulated for retirement," said Vandermillen.

The compounding interest and potential tax savings of stashing money in a retirement plan can have a big impact. Putting away an extra $25 a week or $1,300 a year could potentially result in a tenfold increase in your nest egg over the next few decades. If you start saving $1,300 in a Roth IRA at age 30, for example, and save until you reach 67, you'll have amassed $48,100 in contributions alone, according to Bankrate.com. Factor in a modest annual rate of return of 4 percent, and that extra $25 a week will result in a retirement balance of $110,461 (assuming a current tax rate of 25 percent and a retirement tax rate of 15 percent).

Read MoreOne-third of high earners live paycheck to paycheck

What does it take to squeeze out an extra $25? It's definitely doable. More than half of workers who haven't saved any money for retirement said they could come up with the cash. Cooking at home instead of eating out or ordering take-out food, forgoing soft drinks from vending machines, movies, videos, DVDs or streaming video, coffee from specialty shops and lottery tickets are some of the ways they said they could scrape together the extra dollars.

And a quarter of workers admitted they wouldn't need to give up anything in order to save the extra $25 a week.