USPS Services and Packaging Requirements in 2023

Businesses typically choose between three main shipping partners—USPS, UPS, or FedEx. For many, USPS presents the cheapest option, especially for those who primarily ship lightweight, similarly sized items.

EcoEnclose is proud to work with USPS for many of our shipments. Besides offering great services, their pricing for our samples and smaller orders is hard to beat. Over the years of partnering with USPS, we’ve learned much about how to package things effectively, the best mailer sizes, and the mailers to avoid.

As with any shipper, USPS has many service options and packaging requirements. These can be confusing unless you have hours to dig through their website, and who has time for that? Lucky for you, we did.

To share what we’ve learned, we’ve broken down some of the most important things to know regarding packaging for USPS based on our research and experiences. These are all updated according to the latest regulations as of July 2023.

Specifically, we cover:

• Categories of shipments—what qualifies as a letter versus a flat versus a parcel
• Minimum packaging standards for each shipment category
• Shipping services that USPS offers
• USPS-friendly and eco-friendly mailers from EcoEnclose

Categories of shipments

USPS has three main categories of mailings, defined by the shape, size, and weight of a shipment. To help you visualize what we discuss below, here’s a handy chart directly from USPS.

1. Letter

Letters are any mailing that is:

• At least 3 ½ inches x 5 inches x 0.007 inches thick
• No more than 6 ⅛ inches high x 11 ½ inches long x ¼- inch thick

Standard letters are rectangular with an aspect ratio of less than 1.3 and more than 2.5. (To find the aspect ratio of your letter, simply divide the length by the height.) While mailings that fall out of these aspect ratios (including square envelopes) count as “letters,” they are subject to non-machinable surcharges.

Tip: If you’re wondering how to measure whether your letter is at least 0.007 inches thick, simply compare it to an index card or postcard.

2. Flats or large envelopes

Flats are mailings that:

• Have one dimension greater than 6 ⅛ inches high OR 11 ½ inches long OR ¼-inch thick.
• Are no more than 12 inches high x 15 inches long x ¾ inch thick.
• While USPS dictates that flats or large envelopes must be rectangular, in this instance, square mailings are accepted as “rectangular.”. This shipment category is not subject to aspect ratio requirements.

Tip: If you can fold your mailing down to letter size, it might save you money. However, it’s essential to keep the weight of your mailing in mind, as that will also affect pricing.

EcoEnclose offers several mailers at or under the maximum 12 x 15 inches large envelope size:

• Apparel Mailer (7 x 9 inches, 10 x 13 inches, 12 x 15 inches)
• Kraft Mailer (6 x 10 inches, 8.5 x 12 inches, 9.5 x 14.5 inches)
• EcoX Mailer (6 x 9 inches, 7.5 x 10 inches, 9 x 12 inches, 10 x 13 inches, 12 x 15 inches)
• Rigid Mailers (6 x 8 inches, 9 x 11.5 inches, 11 x 13.5 inches)

3. Parcels

Parcels are mailings that are:

• At least 3 inches high x 6 inches long x ¼-inch thick.
• No more than 108 inches in length and girth combined (a combined 130 inches is allowed for USPS Ground Advantage). Length measures the longest dimension, and girth is the distance around the thickest part (perpendicular to the length).
• No more than 70 pounds.

Basic packaging standards

USPS provides an extensive set of basic standards for all mailings. Most eCommerce companies likely only need to know a small portion of that list. That’s why we’ve pulled what we’ve found to be the most relevant details.

Here’s what you need to know.

Letters

These are always made of paper. Any non-paper envelope (such as a poly mailer) shipped as a "letter" would be considered non-machinable and subject to additional charges. This includes additions like strings, buttons, or clasps. Loose items within paper envelopes may also make the letter nonmachinable, resulting in additional fees.

Flats or large envelopes

These can be made of paper, plastic bags/polyethylene, flat corrugated boxes, or cloth. Polyethylene mailers, like our Poly Mailers, must be at least 2 mils thick for shipments up to 5 pounds and 4 mils thick for shipments up to 10 pounds (and are not acceptable for shipments over 10 pounds). When poly mailers are used, their overhang should not exceed 0.5 inches when the package is lying flat and have a uniform thickness. Any paper used for paper bag packaging or paper wrap packaging must be 50 pounds in strength. Finally, they should be able to bend. Otherwise, they will be considered a parcel.

Note: 1000 mils = 1 inch.

Note: Poly bags are another plastic bag shipping solution we offer, but these are used for inner packaging only.

Parcels

These are usually made ofcorrugated shipping boxes. Parcels over ¾-inch thick (or exceed other dimensions required to qualify as a large envelope/flat) but still relatively thin could be packaged in expandable paper envelopes, poly mailers/plastic bags, paper bags or wrap, or even cloth. Poly mailers must be at least 2 mils thick for shipments up to 5 pounds and 4 mils thick for shipments up to 10 pounds. They are not acceptable for shipments over 10 pounds. Any paper used for paper bag packaging or paper wrap packaging must be 50 pounds in strength.

A non-machinable and/or irregular parcel surcharge may be applied if the above standards aren’t met if maximum weights and dimensions are exceeded, or if a package is oddly shaped or irregular. This is why it’s always best to purchase packaging that you already know is USPS-compliant.

USPS shipping services

USPS has five main categories of shipping services relevant to an eCommerce business. The actual price of shipping will vary based on the service selected, the mailing type (letter, large envelope, or parcel), the actual weight and dimensions of the mailing, and the distance it will travel. Let’s take a look.

First-Class

This service is typically the most inexpensive shipment option and is always the optimal choice if you’re shipping something lightweight. Pricing is not dependent on how far the mail travels, making it an ideal fit for companies that offer free shipping on light items—you’ll know your shipping costs ahead of time. We’d like to note that, as of July 2023, you can no longer send packages through First-Class Services. You must use Ground Advantage, detailed below. Here’s a rundown of First Class services:

• Types of packages: Letters, large envelopes, or flats
• Weight limits: 3.5 ounces or less for letters, 13 ounces or less for large envelopes, flats, or parcels
• Includes: Forwarding and return services
• Cost: Based on weight and shape

Priority Mail

This service offers weight flexibility within quick delivery times: 1 - 3 business days anywhere in the United States. Unlike First Class, Priority Mail shipments are priced based on distance and are calculated by the number of shipping zones the package has to cross to reach its final destination. It’s important to note that it cannot exceed 108 inches in combined weight and girth. Here’s the rundown:

• Types of packages: Letters, large envelopes, flats, and parcels
• Weight: Any shipment under 70 pounds, any mailing over 13 ounces (or a letter over 3.5 ounces)
• Includes: USPS Tracking, forwarding services, and return services, Free Package Pickup, up to $100 of insurance
• Cost: Based on distance, weight, and shape

Priority Mail Express

This is the fastest mail service offered by USPS. It provides guaranteed 1-Day or 2-Day expedited service by 3 pm for any mailable matter. In many locations, it’s also offered 365 days a year. This makes it an excellent option for orders that might have been damaged or incorrect that need to be replaced ASAP, emergency orders, expensive products, or if you’d like to go above and beyond for your customers. Here’s the rundown for Priority Express:

• Types of packages: Letters, large envelopes, flats, and parcels.
• Weight: Any shipment under 70 pounds
• Includes: $100 of insurance coverage, money-back guarantee for late shipment, proof of delivery signature record, Free Package Pickup
• Cost: Based on weight and distance

Media Mail

Media Mail is USPS's cost-effective way to send packages containing media and educational materials (typically quite dense and heavy). Only books (at least eight pages), printed music and test materials, video and sound recordings, printed educational charts, medical loose-leaf pages, binders, or computer-readable media can be sent this way. Video games, computer drives, and digital drives are not eligible for Media Mail prices.

Here’s the rundown:

• Types of packages: Envelopes, flats, or parcels containing accepted media items
• Weight: 70 pounds or less
• Cost: Based on weight
• By shipping via Media Mail, you consent to have your package contents inspected and verified.

USPS Ground Advantage (new service replacing USPS Retail Ground)

Historically referred to as Parcel Post or Parcel Select and, most recently, Retail Ground, this shipping class is for small and large packages, thick envelopes, and tubes. It promises domestic delivery within 3 - 5 business days. If you have a flat package or envelope that doesn’t meet the requirements for First Class, you’ll have to opt for this service. Because it’s a ground service, it’s the primary option for those sending hazardous materials that cannot be transported by plane.

• Types of packages: Parcels or large envelopes being treated as packages
• Weight: 70 pounds or less
• Included: $100 insurance, Free Package Pickup
• Cost: Based on weight, size, and shape

To learn more about USPS's shipping services for small businesses, check out their Business Mail 101 Portal. Or, check out their handy chart comparing services.

USPS 2023 prices

2023 has seen quite a few price changes from USPS. This is both to better align with inflation and to help the Postal Service reach financial stability as part of its 10-year Delivering for America plan. Even with the price increases, it offers competitive pricing and excellent services for eCommerce businesses. The changes, valid as of July 9, 2023, are as follows.

First-Class Mail

Current package rates and prices

You can check out a full list of USPS prices here.

Shop USPS-friendly mailers from EcoEnclose

Shop all of our recycled mailers here and check out a few mailer options below to get started.

Feeling overwhelmed? Contact us today. We are happy to help!

Padded Mailers

Upcycled newspaper sandwiched between recycled Kraft paper. Ideal for shipping fragile items. 100% recycled, 20% post-consumer waste.

For mailer size 10.5" x 15"
- Package weight: 13 oz or more
- Shipping service: Priority
- Package type: Flat/Envelope

Ready to ship  |  Min. 10 units
Customizable  |  Min. 500 units

Apparel Mailers

Creasing for expandability and premium presentation. Ideal for shipping soft goods. 100% recycled, 97% post-consumer waste.

For mailer size 12" x 15"
- Package weight: 13 oz or more
- Shipping service: Priority
- Package type: Flat/Envelope

Ready to ship  |  Min. 25 units
Customizable  |  Min. 500 units

Kraft Mailers

Lightweight paperboard and affordable price point. Ideal for shipping lightweight soft goods. 100% recycled, 90% post-consumer waste.

For mailer size 6" x 10"
- Package weight: 3.5 oz or less
- Shipping service: First Class
- Package type: Letter

Ready to ship  |  Min. 25 units
Customizable  |  Min. 500 units

Additional Sources

https://pe.usps.com/businessmail101

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