While most shippers compare priority mail to parcel post by the difference in cost and in shipping time, there are more significant differences to consider. Both types of mail are handled and sorted with care, but the extra cost associated with priority mail gets you service and packaging products not included with the cost of parcel post mail.


Parcel post is now known as Retail Ground service.

Comparing Delivery Times

Delivery time is the first thing that comes to mind when comparing retail ground service vs. priority mail. Service standards for priority mail are one to three business days. Retail ground delivery times range from two to eight business days nationwide. Media mail, which can be used to send media and educational materials, also takes two to eight business days.

Comparing Shipping Costs

The United States Postal Service (USPS) determines shipping costs through a combination of package weight and shipping distance for both priority mail and retail ground service. The heavier a package is and the further it has to travel, the greater the shipping cost. Surprisingly, the difference between priority mail and parcel post/retail ground is just pennies at times.

Media mail can also be a cost-saving option if you are sending books, music or sound recordings. Unfortunately, media mail cannot be used for video games or computer drives.

If you are sending packages in bulk, you may also want to consider comparing parcel select vs. first class mail. Parcel select is USPS's economical ground shipping service, but it is priced by volume and you have to transport the packages to a bulk mail center.

Paying for Return and Forwarding Service

What if your package is not deliverable as addressed? We all think we have the correct address on our packages, but every day the USPS handles tens of thousands of packages that are undeliverable.

When you ship your package by priority mail, the cost of forwarding the package to the addressee's new home or returning the package to you is included in the price you pay when you mail it. The lower price paid for retail ground service does not include forwarding or return service. When your retail ground package is forwarded or returned, the USPS will collect postage for that service.

Paying for Packaging

The USPS provides envelopes, boxes, mailing labels and tape free of charge to customers using priority mail. The expense of packaging products adds up quickly. Boxes and rolls of packaging tape purchased at retail outlets can cost upwards of $3.00.

The USPS is vigilant when it comes to the use of its packaging products. Mailers who attempt to use priority mail packaging for their retail ground shipments will have their items returned to them for postage due.

What About Flat-Rate Priority Mail?

The concept of flat-rate boxes and envelopes is simple: it is one price to ship that size envelope or box anywhere in the United States, regardless of weight or destination. While flat rates have simplified priority mail, customers should be aware that any package over 16 oz. must be handed to a postal employee as a security measure.

Flat-rate priority mail prices as of 2019 are as follows:

  • Priority Mail Flat Rate Envelope: $7.35
  • Priority Mail Small Flat Rate Box: $7.90
  • Priority Mail Medium Flat Rate Box: $14.35
  • Priority Mail Large Flat Rate Box (domestic addresses): $17.60
  • Priority Mail Large Flat Rate Box (APO / FPO destinations): $17.60

USPS also offers prepaid forever priority mail flat-rate packaging. This means that once you purchase the packaging, you never need to pay additional postage, even if rates increase before you use the packaging.