UPS, the Sandy Springs-based logistics company, expects more online sales to contribute to a peak season that is larger and more compressed than in years past.

UPS expects to deliver more than 120 million packages in the week before Christmas, a 6 percent increase from the 113 million it delivered during last year's peak week. The company will hire 55,000 temporary workers to aid in the spike in packages, including 1,247 in Atlanta. That's about 70 fewer people here than last year.

The peak season used to stretch from Thanksgiving to Christmas, but the company said rising online sales have driven changing shipping patterns.

"We have seen, over the years, the window shorten because they [holiday shoppers] know they can wait," UPS spokeswoman Elizabeth Rasberry said. "More and more is being shipped online."

While UPS did not estimate how many packages it will deliver for the duration of its peak season, saying the compression makes it difficult to estimate total seasonwide shipping numbers, it did say it expects a modest increase in total holiday shipping.

Five of the last 10 days before Christmas will have delivery levels that meet or exceed 25 million packages a day, the company said. Last year, there was only one day with more than 25 million deliveries.

The company's busiest day will be Dec. 22, when nearly 26 million packages will be delivered. FedEx said earlier that it expects to deliver 17 million packages on its busiest day, Dec. 12.

Rasberry said the shift aids last-minute shoppers, who can make online orders closer and closer to the holidays.

Offers of free shipping and wider selection also have driven customers to do more of their shopping online, said Ron Wiener, CEO of EquaShip, a parcel delivery service. He said e-commerce as a category is growing.

The National Retail Federation estimates shoppers will spend $465.6 billion during the holidays, a 2.8 percent increase over 2010.

UPS’ hiring levels related to peak season are up this year; last year, the company brought on 50,000 additional workers.