They say the holiday mailing rush will only intensify through Christmas.
Bill Burgoon with FedEx offered tips in order to avoid steep costs associated with late deliveries.
"FedEx Ground is going to be your cheapest option. You have until December 17th to ship it and we'll guarantee by Christmas," said Burgoon.
Burgoon said after the 17th, FedEx shipping costs are expected to escalate.
For USPS, the deadline is December 20th, while UPS says December 19 will be the last date to ship without incurring additional fees.
UPS Store owner Rich Yee says it is important to keep the size of the package in mind.
"If you're shipping something to a relative out of state or out of the country, try to avoid something that is enormous. That way the shipping costs are usually higher because of the dimensional weight," said Yee.
Or, opt for gift cards like Denise Stipes.
"Even if it comes down to gift certificates, I have to get everything done by a certain time so everything makes it and everyone is happy at Christmas time," said Stipes.
For those who still need to ship, here are some important dates for delivery before Christmas, and links with additional tips and apps:
Dec 20 first class mail
Dec 21 priority mail
Dec 22 express mail
Dec 17 ground
Dec 22 FedEx
Dec 19 3 day select
Dec 21 Next Day Air
USPS shipping information:
Tips on How to Pack Items