Next up: Innovation Delivered
Join us on August 7th for Innovation Delivered, a virtual ecommerce event with over 40 speakers across 30 sessions. Catch practical insights, product previews, and more.
Effortless returns and exchanges
Turn returns into revenue with effortless exchanges, a branded customer portal, and centralized tools that cut manual work and unify returns across every channel.
New features that fuel growth
Power growth at every stage of fulfillment. Our enhanced tools for inventory, returns, and analytics help you scale smarter—from order to outcome.
Who We Help
use cases
Products
Core Features
Featured Integrations
Integrations
Resources
Help Center
Shipping with USPS? If you’re choosing between First Class and Priority Mail in 2025, this guide breaks down everything you need to know: costs, speed, package limits, and when to use each service. Typically, the deciding factor in making a decision in First Class vs Priority Mail comes down to weight. If a parcel weighs less than 16 ounces (with Commercial Pricing), it makes the most sense to use First Class Mail. However, there are instances when the choice is not so black and white. For instance, First Class Mail is slower than it used to be. There are instances when one service wins over the other. We’ll go over a few situations where one service may win over the others.
USPS First Class Mail is an economical way to ship parcels and thick envelopes weighing under 16 oz. With retail rates, the maximum weight is 13 ounces. This is why it’s good to access Commercial Pricing through a shipping service like ShipStation. The maximum allowable size for parcels are dimensions of 22″ x 18″ x 15″. Delivery usually takes 2–5 business days for parcels to reach their final destination. Letters are a little faster since they sort more quickly.
First Class Mail may sound fancy but it doesn’t have the same meaning as something like flying first class—the most premium USPS service is Priority Mail Express. First Class Mail is actually a class of mail used to ship letters, thick envelopes, padded envelopes, and lightweight packages. First Class Mail gets its name because is considered the top tier of mailed letters in comparison to:
If your items weigh under a pound, such as shirts, they’ll be a great candidate for USPS First Class Mail. Because they’re lightweight and durable, try shipping in a poly mailer to cut down additional costs. There are also other options other than the USPS to ship clothing with. To find out which service works best for whatever you’re sending, check out our guide on how to ship clothing.
USPS Priority Mail® is a service that lets you send parcels weighing up to 70 lbs domestically. Not only can parcels be heavier with Priority Mail, they can also be larger. The maximum dimensions are 108” in combined length and girth (the length of the longest side, plus the distance around the thickest part of the package). Generally, USPS Priority Mail takes 1-3 business days to reach its final destination.
USPS Priority Mail Express® provides all the features of standard Priority Mail just with more express options. In fact, many destinations offer guaranteed overnight delivery while others offer two-day delivery. Though a little pricier, it may be the best option for customers that need their orders ASAP.
Shoes are almost always going to ship using Priority Mail (Unless they weigh less than 16 oz). Check to see if Flat Rate options offer discounts over standard Priority Mail packaging.
USPS First Class Mail is typically used for smaller, lighter parcels—weighing under a pound—with items whose insured value is not very high. Items over a pound and/or items of higher value work better with Priority Mail.
*Exceeding these maximum restrictions may result in a $100 charge applied to you by the USPS.
A major advantage of USPS Priority Mail is that it includes coverage in the event that a parcel becomes lost or damaged in transit. First Class Mail offers no default coverage, however, both Priority Mail and First Class Mail do allow additional coverage to be purchased through the USPS or through a third-party provider such as Shipsurance.
First Class Mail is a more economical shipping option than Priority Mail. If you would like a breakdown of the shipping rates available to you, check out these rates available to any ShipStation user through their complimentary Stamps.com account.
Now that First Class Mail uses USPS zones when rating, it’s easier to compare transit times. Let’s take a look at the estimated delivery time it takes for different locations around the US and globally:
USPS First Class Mail International® (FCMI) allows heavier parcels than its domestic counterpart. The max weight limit for FCMI parcels is 4.4 lbs. They also can take longer to reach their final destination. This service also doesn’t offer tracking to all locations and estimated delivery timeframes may not be included. So, while it is an economical option, it may not be the best option for you and your customers. After all, tracking and timely delivery increase consumer satisfaction.
USPS Priority Mail International® (PMI) typically cuts shipping time down significantly. Because of this, it is a little bit more expensive than First Class Mail. With its more robust tracking and heavier weight limits of up to 70 lbs, PMI provides more of the features that international customers would expect.
USPS Priority Mail Express International® lets you ship large parcels in the same way as USPS PMI but it cuts transit times down even further. Check the table below for even more information!
USPS Media Mail is the USPS’s more affordable, slower option for shipping CDs, vinyl records, DVDs, books, bound print media consisting of 8 or more pages. Unlike other USPS services, the USPS can inspect the package to make sure the contents are approved materials without first authorizing a search warrant.
Shipping things like vinyl records and books is more affordable thanks to Media Mail. It also works for CDs, DVDs, and other physical media. If expedited delivery is important, consider upgrading to First Class Mail or Priority Mail, depending on the weight or insured value.
From First Class to Priority Express, ShipStation automates packaging, applies cheapest rates, and lets you batch-print labels in seconds.
Use Priority Mail for packages over 16 oz, or if speed and insurance coverage are critical. It’s also ideal for shoes and higher-value items.
Yes, all First Class packages now include tracking, though tracking updates may be slower than with Priority Mail.
Yes, insurance can be added manually through USPS or third-party providers like Shipsurance. It’s not included by default.
James Messer is a copywriter specializing in shipping, logistics, and ecommerce.