For anyone behind on their holiday shopping, Wednesday might be the day to catch up.

December 18 is the sixth annual Free Shipping Day, where businesses waive shipping fees on orders of any size and customers are guaranteed delivery by Christmas Eve. Although Free Shipping Day doesn’t have the same name recognition as Black Friday or Cyber Monday, 930 businesses are participating this year, including Under Armour, 1-800-Flowers, Zappos, and Nasty Gal, according to the event's website.  

Companies must decide whether a potential increase in sales outweighs the costs of waiving shipping fees. Even beyond sales though, the event is an excellent opportunity to increase brand recognition, said Yanique Woodall, the vice president of public relations for 1-800-Flowers. "We know that this is something that resonates with consumers," she said. "It made natural sense that we would participate."  

Free Shipping Day has grown rapidly since its first edition in 2008. The event’s website boasts that spending on the day has exceeded $1 billion over the past two years, topping Black Friday’s online spending over the same period. 

For nearly 30 percent of people who don't shop online, delivery costs are the chief reason, Forbes reports, citing research from comScore. Free Shipping Day could be a way to attract such consumers. 

"At the end of the day, most families have a set holiday spending budget--it is about $900 per family," said Patricia Norins, a retail consultant and spokesperson for Small Business Saturday. "So it is critical for retailers to capture as much of that pie as possible and this could be another event that encourages consumers to take action on a specific day.”