Quick, guess how much spare change is lurking in the cushions of your sofa.
Chances are, you are underestimating.
Coinstar, a division of Outerwall that operates kiosks where consumers can convert coins to cash or gift cards, surveyed consumers in October, asking them to estimate the amount of spare change they have lying around. The average response was just over $28. But the company says the average amount of coins that consumers convert to gift certificates at its kiosks is $56.
"Consumers underestimate how much change they have by a factor of a half," said Michael Skinner, president of Coinstar. "They don't think about it. It shows up in places like a cupholder in their car."
Coinstar employees, Skinner said, "might be the only ones who think about the value of pennies."
That extra weight in your wallet is probably a good thing, since more 67 percent of the survey respondents who said they set a holiday budget expect to go over their self-imposed spending limit, by an average of $148.
Still, even with that overspending and found money, early estimates suggest the holiday shopping season may be a bit of a mixed bag for retailers. The National Retail Federation expects total holiday sales to increase, but predicts that the average holiday shopper will spend $738 on gifts, down 2 percent from $752 spent in 2012.
(Read more: A naughty or nice Christmas at stores? Depends on whom you ask)
The late arrival of Thanksgiving this year is also putting pressure on retailers, since the holiday shopping season is compressed. Some are even starting their holiday specials ahead of Black Friday.
(Read more: Is Black Friday dead?)
So it may be time to get out there. The deals are already coming fast and furious, like Amazon's Black Friday Week promotion and stores like Sears offering pre-Black Friday bargains. Plus, those pockets are jingling.
—By CNBC's Kelley Holland. Follow her on Twitter @KKelleyHolland.