To make sure packages arrive in time for the holidays, you'll need to know the shipping deadlines for the major carriers. There's not a single date to note: "Last day to ship" guidelines depend on the carrier and a variety of other factors.

This year's shipping deadlines might be especially tricky, according to Consumer Reports, which has this advice for Christmas gift-givers: "Don't be fooled into thinking that Dec. 25 means you have a cushion of 12 more days. Most major retailers — and package shippers — anticipate online shopping will be off the charts this year and place a tremendous strain on package delivery systems this holiday season."

Whether you're getting a last-minute Sunday delivery from Amazon, are mailing care packages abroad for loved ones in the military or have other pressing shipping needs this holiday season, make sure your gifts get there on time with these holiday shipping deadlines:
 
Free shipping day

If you take the "If it's free, it's for me," approach, you'll want to check out Free Shipping Day Dec. 15. More than 600 online merchants will participate, offering hundreds of items that will arrive by Christmas Eve when shipped for free on Dec. 15.

FedEx

For guaranteed Christmas delivery shipping within the U.S.:

Dec. 11: Last day to ship via FedEx SmartPost
Dec. 15: Last day to ship via FedEx Ground
Dec. 18: Last day to ship via FedEx Home Delivery
Dec. 19: Last day to ship via FedEx Express Saver
Dec. 20: Last day to ship via FedEx 2Day and FedEx 2Day A.M.
Dec. 21: Last day to ship via FedEx Standard Overnight, FedEx Priority Overnight, and FedEx First Overnight
Dec. 25: Last day to ship via FedEx SameDay City (Priority), FedEx SameDay City (standard), and FedEx SameDay

Shipping deadlines vary for packages headed to Puerto Rico and international destinations including Canada and Mexico.

If you're interested in Saturday delivery on Dec. 23, the following FedEx Express® services will deliver that day if you select that option: FedEx First Overnight®, FedEx Priority Overnight®, and FedEx 2Day®. FedEx Ground does not deliver on Saturday, Dec. 23, but FedEx Home Delivery will deliver that day with no additional charge.

The FedEx SameDay service (and some other FedEx expedited services) allows you to ship on Christmas Day or any other day of the year.

Find the delivery time and FedEx delivery choices for your U.S. and international shipments by using the Get Rates & Transit Times application at fedex.com.

Download an easy-to-print deadline calendar for the office or to keep posted at home on the FedEx website.
 
UPS
 
To make sure your package arrives in time for Christmas via UPS, get a quote that compares shipping charges and delivery times for UPS domestic and international services.
 
If you're shipping within the U.S.:

Dec. 18: Last day to ship UPS 3 Day Select, with delivery on Friday, Dec. 22
Dec. 20: Last day to ship via UPS 2nd Day Air, with delivery on Friday, Dec. 22
Dec. 21: Last day to ship via UPS Next Day Air, with delivery by Friday, Dec. 22.
Dec. 21 is also the last day to ship via UPS 2nd Day Air with Saturday Delivery option. (Saturday Delivery is not available to all ZIP codes.)
Dec. 22: Last day to ship via UPS Next Day Air with Saturday Delivery option. (Saturday Delivery is not available to all ZIP codes.)

Note the UPS Saturday delivery carefully, and note that certain other packages and services may require an additional day of transit time per UPS warnings.
 
For international shipping deadlines and other holiday-related information, such as pickup and delivery schedules, see the Holiday Shipping with UPS website.
 
And to make sure your package is in good shape to get there in time for Christmas, UPS has packaging tips and guidelines on its website.
 
U.S. Postal Service

The most important thing to note about holiday shipping deadlines for the USPS is that these are only recommended send-by dates for "expected" delivery by Dec. 25. The postal service notes on its website that "actual delivery date may vary and is based on origin, destination, post office acceptance time and other conditions."

For mail and package shipping within the continental U.S.:

Dec. 14: Last day to send packages via Retail Ground
Dec. 19: Last day to send packages via First Class Mail
Dec. 20: Last day to send packages via Priority Mail
Dec. 22: Last day to send packages via Priority Mail Express
 
As for the express mail options, note that the USPS will honor its money-back guarantee for Priority Mail Express shipments mailed Dec. 22 through Dec. 25th only if the shipment is not delivered or delivery is not attempted within two business days.
 
For mail and package shipping to Alaska:
Dec. 20: Last day to send packages via First Class Mail and Priority Mail services
Dec. 21: Last day to send packages via Priority Mail Express

For mail and package shipping to Hawaii:
Dec. 15: Last day to send packages via First Class Mail and Priority Mail services
Dec. 20: Last day to send packages via Priority Mail Express

The deadline for shipping packages internationally, including to overseas military bases, varies based on the destination and type of delivery service.
 
For more information

FedEx last days to ship for holidays
www.fedex.com/us/holiday/last-days-to-ship.html

UPS holiday shipping guide
www.ups.com/us/en/help-center/shipping-support/days-of-operation-us/holiday-shipping.page

Holiday shipping deadlines, USPS
www.usps.com/holiday/holiday-shipping-dates.htm