Knoxville (WVLT) -- Sometimes, the search for that perfect Christmas toy or outfit ends with an envelope.

Almost 90 percent of shoppers will buy one or more gift cards.

That figure is great for stores because you might not know it, but when it comes to determining the worth of a gift card, it’s all in the fine print.

If you don't know what to get your favorite aunt or crazy cousin for Christmas, it's always a good idea to grab your plastic and buy some plastic.

"It seems like the easier thing to do,” said holiday shopper Melissa Needs. “That way they can go out and pick something out that makes them happy, they can go after Christmas and get more for their money."

Gift cards make great gifts for Melissa’s family.

"A lot of us, you just don't know what you want," she said.

But before you swipe, Dr. Ann Fairhurst with UT says dig a little to get your money's worth.

"There may be some restrictions on where you can purchase, there may be a delivery fee," said Dr. Fairhurst who is a professor of Retail Consumer Sciences.

That is especially true with the ones with credit card-like features.

They can charge you fees based on where you shop and what type of card you have issued.

You should also make sure there are no usage limitations.

Some companies may only allow you to use cards in their online or catalog store.

"If you purchase Aunt Sally a $50 gift card and it can only be used online and Aunt Sally doesn't have a computer that's probably not going to be a good thing," said Dr. Fairhurst.

It's also not a good thing, because if your loved ones decide to wait to spend it, they could end up without a gift.

Check gift cards for expiration dates and maintenance or inactivity fees.

If you don’t, you could get charged for not using your card in time or not using it at all.

"If you don't use it after a certain time frame then they might charge two or three dollars to that card every month after that," said Dr. Fairhurst.

But Melissa doesn't think that will be a problem for her family.

"We all know it's going to get used pretty much after Christmas when there are big discounts and when the stores are clearing out there winter stuff to get their spring stuff," she said.

You can find out more holiday shopping tips by clicking on the Hot Key