USPS Mail Types: Classes of Mail, Speed, Cost, and More

Verified & Reviewed

Written By

Written By

Subscribe for More

Shipping through USPS is a popular choice for many ecommerce businesses. With USPS, you get cost-effective shipping options comparable to FedEx and UPS. Their flat-rate shipping options are also a popular choice because they allow you to forecast your costs. 

One major benefit of shipping through USPS is how simple it is. All you have to do is print labels and drop packages off at your local USPS Post Office or a mailbox (depending on quantity). But which types of shipping options and mail classes are best for your business?

In this guide, we’ll go over the USPS mail types, prices, delivery options and more so you’ll know which options to pick when using USPS for ecommerce shipping.

Know your mail classes: why it’s important for ecommerce businesses

Your business is shipping hundreds or even thousands of packages a month. Even a small $1-$2 dollar difference in shipping costs can have a big impact on your profit margins. You could have packages delivered within a couple days at a premium shipping cost, but you could see up to 30% cost savings if you opt for four-day delivery. 

This is why it’s important to know the USPS mail classes. Knowing the different mail classes allows you to choose the right speed and cost for each package so you can offer the right shipping options for customers without cutting into your profits. 

USPS mail types: the 6 classes of USPS mail

The USPS divides mail into six different services called classes. Each mail class has different service levels, postage prices, and pre-sort requirements.

For most shipments, the content of the material and postage will determine the class of mail you select. Here are the 6 classes:

  1. Priority Mail Express (the fastest shipping option)
  2. Priority Mail
  3. First-Class Mail
  4. USPS Marketing Mail
  5. Periodicals
  6. Package Services/USPS Retail Ground

Not sure which class of mail is right for your mailing? Look at the matrix below to determine what class of mail best matches your priorities. For most ecommerce businesses, Priority Mail, Priority Mail Express, and First-Class Mail will be your most used mail classes.

USPS classes of mail

1. Priority Mail

Priority Mail is often considered the best value for ecommerce shipping. It’s not as fast as the 1-2 day shipping options available with Priority Mail Express, but it offers speedy delivery at a much more convenient shipping cost to sellers. 

The cost for Priority Mail is determined by how far packages travel to get to their destination (the farther it travels the more you pay in postage). The actual distance is measured by “zones.” Shipping zones range from zone 1 (local, close to you) to zone 9 (very far away from you). The farther the mail travels, the more zones it crosses, and the more postage you pay. 

The USPS offers special prices for Priority Mail Flat Rate Envelopes or Boxes. With a weight limit of 70 lbs., anything that fits into a USPS-provided Priority Mail Flat Rate Box can be mailed for a flat rate price. Many Priority Mail envelopes, boxes, and tubes are available for free from your local Post Office. All packaging can be ordered online at

2. Priority Mail Express

Priority Mail Express is the fastest delivery option offered by the USPS. It provides guaranteed 1-Day or 2-Day expedited service by 3 p.m. for any mailable package. Even better, it includes $100 of insurance coverage. Priority Mail Express can even deliver 365 days a year in many locations throughout the US. Sunday or holiday can also be done at an additional cost.

If getting your package to its destination overnight is your highest priority, then Priority Mail Express is the best choice. However, many ecommerce businesses don’t need overnight delivery for their packages. Priority Express Mail will likely only be used for extreme cases or if you want to offer next-day delivery as a competitive advantage for your business.

Priority Mail Express prices are based on the weight of the piece and how far the piece travels, except when USPS-provided Priority Mail Express Flat Rate packaging is being used.

3. First-Class Mail

First-Class Mail is another popular option if you’re selling lightweight products. With a delivery speed of 1-3 days, it offers a cost-effective shipping option for growing ecommerce businesses. 

First-Class Mail is $0.55 for each envelope regardless of how far the mail travels. First-Class Mail postage includes forwarding and return services. You can expand the offerings of First-Class Mail by adding extra services such as Registered Mail and Certified Mail. These services are available for an additional fee.

Many beginning mailers use First-Class Mail postcards and letters because, if you mail at single-piece prices, there’s no special payment method, no mailing permit, and no extra time to presort the mail. You simply put a stamp on it and drop it in a USPS mailbox or Post Office. 

4. USPS Marketing Mail

Ecommerce businesses use USPS Marketing Mail to send marketing collateral. If you have a catalogueueueue, flyers, coupons or anything promotional to send, consider using USPS Marketing Mail.

All USPS Marketing Mail prices are bulk prices, and each mailing must meet a minimum quantity of 200 pieces or 50 pounds of mail. There is no single-piece USPS Marketing Mail postage. In USPS Marketing Mail, there are prices for letters, flats/large envelopes, parcels, Marketing parcels, and Parcel Select Lightweight parcels.

5. Periodicals

The Periodicals class of mail is designed for newspapers, magazines, and other periodical publications. As an ecommerce business, you will almost never use this option unless you have a physical print magazine. 

6. Package Services/USPS Ground

Package Services is a collective term used for three specific classes of mail: Bound Printed Matter, Media Mail, and Library Mail. Each subclass is best suited for a certain kind of mail. As an ecommerce business, these options likely won’t apply to your business. 

Package Services and USPS Retail Ground packages don’t receive expedited service. These don’t include free forwarding and return.

USPS Retail Ground is mainly intended for single-piece mailings which consist of any packages that aren’t required to be mailed as First-Class Mail and include USPS Tracking at no additional charge. It’s commonly used for gifts and merchandise. There are no bulk prices for USPS Retail Ground.

Which USPS mail class is right for your ecommerce business?

For most ecommerce businesses, Priority Mail meets your standard delivery needs and is the most cost-effective option. Due to its attractive flat-rate options and moderate delivery speed, you will see many benefits from using Priority Mail as your default USPS shipping method. It will depend on the weight of the package you are shipping, how fast it must arrive, and how much you want to spend.

Priority Mail Express and Marketing Mail are also good options depending on the types of products and items you’re shipping. 

Fastest: Priority Mail Express

Overnight and 2-day shipping are becoming popular shipping options for many ecommerce businesses because customers want their products delivered quicker than ever before. If you want to offer faster delivery options, Priority Mail Express will be a good option for you. Just know that it will be a much higher shipping cost than Priority Mail, so charge your customers accordingly. 

Most cost-effective: Priority Mail

Priority Mail is a day or two slower than Priority Express Mail, but it is also much cheaper. As we said before, this is a great default shipping option when shipping through USPS.

For specific items: Marketing Mail & Package Services

These services are for marketing-related items only. If you’re shipping marketing collateral, then these are the services for you. There are many benefits to still using direct mail for your ecommerce business, so consider using Marketing Mail if you want to send promotional materials. 

Get USPS shipping discounts, with ShipBob!

Depending on how many packages you ship, it’s possible to get volume discounts with USPS. You’ll have to reach out to a USPS representative and then work with them on getting the discounts set up which can take up to a few weeks. There’s also an easier method for getting USPS shipping discounts: by partnering with ShipBob!

ShipBob helps ecommerce businesses throughout the country get steep discounts on postage. If you ship often, ShipBob discounts could save you hundreds or thousands of dollars a year!


Shipping with USPS is a great option for your ecommerce business due to its simple cost structure and flexible shipping options. Getting started with USPS is easy and can save you money when compared to couriers like UPS and FedEx at the cost of giving up quicker delivery times.

If you need help with USPS shipping and want shipping discounts, learn how ShipBob can make the USPS shipping process easier. To get started, click on the button below.

Order fulfillment services

You omnichannel fulfillment partner that's an extension of your brand, from unboxings to 2-day shipping.

Warehouse management

Have your own warehouse? Get ShipBob WMS to reduce mis-picks, save time, and improve productivity.

Global scalability

Grow into new geographies with ShipBob's international presence in the US, UK, EU, Canada, and Australia.

Written By:

Shannon Callarman is a Content Marketing Specialist at ShipBob. She researches and writes everything you need to know about the latest trends and best practices in ecommerce.

Read all posts written by Shannon Callarman