Online shopping is expected to drive record package volumes for parcel-delivery companies this holiday season.

The National Retail Federation forecasts online sales in November and December to increase between 6 and 8% over 2014 to as much as $105 billion. The trend is driven by savvy shoppers looking for the best deals while avoiding the stress and inconvenience of visiting brick-and-mortar stores during the holidays. The NRF predicts record use of mobile devices for holiday shopping — 21% of smartphone owners and 34.5% of tablet owners say they will use their devices to purchase holiday merchandise.

The activity will keep delivery services on their toes. FedEx anticipates a 12% increase in holiday volume over last year, to a record 317 million packages.

“The shift in consumer shopping patterns, fueled by the rise of e-commerce, continues to drive our volume,” said FedEx CEO Frederick W. Smith. “Our strategic investments, unmatched flexible global network, and more than 325,000 dedicated team members around the world are ready to help the holidays arrive again this year.”

Holiday Shipping Volumes

UPS is also expecting a percentage increase in the double digits — 10% — and is preparing to deliver a record 630 million packages between Black Friday and New Year’s Eve.

U.S. Postal Service mail carriers will also have their arms full of packages. The agency said it expects an increase in package deliveries of 11% over 2014 to 600 million. Like last year, the post office will offer Sunday package deliveries in some major cities beginning Nov. 29.

2015 USPS Christmas Shipping Deadlines

• Nov. 7 – APO/FPO/DPO Standard Post
• Dec. 8 – Priority Mail Express International
• Dec. 15 – Standard Post
• Dec. 19 – First Class Mail
• Dec. 19 – Global Express Guaranteed
• Dec. 21 – Priority Mail
• Dec. 23 – Priority Mail Express