We are only days away from the Black Friday frenzy -- big box stores will be slashing prices on popular items, enticing shoppers to roll in early for mega savings.

But how much are you really saving? A WalletHub study shows some items may be more expensive on Black Friday than their current price.

Whether you're walking -- or running -- through the doors, there's one thing shoppers hunt for on Black Friday: the best deals.

"This year, the number to keep in mind is 37 percent, that's the average discount across all the 35 top retailers," WalletHub analyst Jill Gonzalez said.

She said anything less than that may not give you the most savings.

"Last year, the average across retailers was 39 percent, the before in 2015, it was 40 percent -- we're actually seeing the average discount decrease across these last few years at least," Gonzalez said. "But you have to keep in mind a lot of retailers are offering more discounts year round to keep up with Amazon.com, so it does tend to balance out a little bit."

The personal finance website released its list of the top stores offering the biggest discounts -- two include Kohl's and J.C. Penney, offering an average of at least 62 percent off. Gonzalez says shoppers will have the best luck getting deals on books, movies, music, video games (software only), and toys, with up to 50 percent off.

But if you're looking for furniture, clothing, or jewelry, you may want to sit this one out. These categories have the lowest discounts with about 7 to 8 percent off.

"There are better times to buy in these categories, so apparel and accessories -- if you can actually wait just a few more days for cyber week, that's when you'll see better discounts on those items,” Gonzalez said.

And with online shopping comes the push for credit card sign ups. WalletHub says stores will offer items with deferred interest, a potentially dangerous financial situation, if you don't read the fine print. One late payment can set you back, applying charges to your entire original purchase amount and costing you more.

"These cards offer one of two things: zero percent financing or a discount for your first purchase," Gonzales added. "So go with that discount if that's an option. If it's not an option, make sure you are paying for everything in that introductory period or sign up for a regular credit card that does not have deferred interest as an option.”

For more tips on Black Friday deals, click here.