When's the Last Day to Mail Christmas Presents?

Time is running out for holiday gift and card shipping through the U.S. Postal Service.

Mail parcels and packages by Dec. 14 for parcel post delivery by Christmas, and cards by Dec. 21, the post office's blog advises.

If you miss those days, though, you're still okay—as long as you're fine with paying a little extra. Here are the absolute-last-day deadlines to keep in mind, according to the U.S. Postal Service's holiday calendar:

• Dec. 14: Last day to ship via Parcel Post for delivery by Christmas.
• Dec. 17: Last day to ship to military for delivery by Christmas.
• Dec. 19: Last day for most international shipping for delivery by Christmas.
• Dec. 20: Last day to send First-Class Mail for delivery by Christmas.
• Dec. 21: Last day to send Priority Mail for delivery by Christmas.
• Dec. 22: Last day to send most Express Mail for delivery by Christmas.

One more date to keep in mind is Monday, Dec. 18: Traditionally, the post office's "busiest day is ... the Monday before Christmas as people mail cards and packages they prepared over the weekend," The Huffington Post reported last year.

A good way to cut down on time spent waiting in line is to order your holiday stamps through the post office's website.

This year's holiday stamps offer something for everyone: a fun "Santa and Sleigh" assortment, a "Holiday Baubles" assortment, Hanukkah and Kwanzaa stamps, a depiction of a Madonna-and-child painting by Raphael and a "Holy Family" stamp.

All of these holiday stamps are "Forever" stamps, meaning that they will be valid forever—even after a new increase in the price of stamps.