Note: As of October 19, 2022, ShippingEasy now offers the lowest USPSⓇ shipping rates in the industry, and the rates reflected in this blog are prior to this change. For more information on these new rates, check out our blog!
“What are USPS Flat Rate Boxes?” is a question that often pops up in the shipping world. And, to be honest, it’s a big question. Not only are USPS Flat Rate Boxes are an offering from USPS Priority Mail, but there are different sizes and box options to choose from and discuss. To give you the full scoop on USPS Flat Rate Boxes, we’ll give you a breakdown of the service itself, Regional Rate Boxes, and a few guidelines (as well as a Table of Contents to make everything easily accessible).
Table of Contents
- What is USPS Priority Mail® Flat Rate?
- What are USPS Priority Mail® Flat Rate Boxes?
- USPS Priority Mail® Flat Rate Envelopes?
- USPS Priority Mail® Flat Rate Small Box
- USPS Priority Mail® Flat Rate Medium Box
- USPS Priority Mail® Flat Rate Large Box
- USPS Priority Mail® APO/FPO/DPO Large Flat Rate Box
- What is USPS Regional Rate shipping?
- When should you use Flat Rate shipping?
- Do USPS Flat Rate shipments come with a tracking number?
- How can ShippingEasy help automate my packaging choices?
Note: The rates in this blog post are the 2022 USPS rates. For the current 2023 USPS rates, visit our USPS 2023 Shipping Rate Changes: Flat Rate, Priority, First Class, w/Tables blog!
What is USPS Priority Mail® Flat Rate?
USPS Priority Mail Flat Rate is one of the most commonly used services because you pay one shipping rate for your package, regardless of its destination and up to 70 pounds. Yes, you read that correctly. Whether you’re shipping a 20-pound package across town or across the country, your rate is going to be the same.
This service type is offered for both standard Priority Mail shipping and Priority Mail Express. Both also include standard tracking, up to $50 in insurance, and typically deliver in 1-3 days (including Saturday at no additional charge). You can even schedule pickups, so you don’t have to drive to the local post office.
There are three main Flat Rate Box sizes, including:
One of the biggest perks of the USPS Flat Rate packaging is you can order these shipping supplies from USPS for free, and they’ll deliver them straight to your home or office. Also, if you use ShippingEasy, you’ll get Commercial (aka discounted) USPS shipping rates. Take a look at the discounts on standard Priority Mail Flat Rates below:
| Priority Mail Flat Rate |  | 2022 Retail | Savings |
|---|---|---|---|
| Flat Rate Envelopes | $7.75 | $8.95 | $1.20 |
| Legal Flat Rate Envelope | $8.05 | $9.25 | $1.20 |
| Padded Flat Rate Envelope | $8.45 | $9.65 | $1.20 |
| Small Flat Rate Box | $8.25 | $9.45 | $1.20 |
| Medium Flat Rate Box | $14.25 | $16.10 | $1.85 |
| Large Flat Rate Box | $19.20 | $21.50 | $2.30 |
| APO/FPO/DPO Large Flat Rate Box | $17.70 | $20.00 | $2.30 |
| *must use boxes |
Did you know you can order some free USPS supplies from your ShippingEasy account? Found out how in our blog!
What are USPS Priority Mail® Flat Rate Boxes?
The only real downside of USPS Flat Rate is you have to use USPS-branded boxes to use the service; you can’t use USPS Flat Rate shipping in a plain brown box or your own branded packaging. Also, everything needs to fit comfortably inside your USPS Priority Mail boxes and not bulge or distort the box.
As the weight of your package or distance traveled increases, the benefit of using the various USPS Flat Rate boxes also increases. Let’s dive into what USPS Flat Rate packaging is available to use and how each of them can benefit your business.
As the weight of your package or the distance it’s going increases, the benefit of using the various USPS Flat Rate boxes also increases. Let’s dive into the available USPS Flat Rate packaging and how each of them can benefit your small business.
USPS Priority Mail® Flat Rate Envelopes
There are three types of envelopes available in USPS Flat Rate shipping, and each of their dimensions are:
- Priority Mail Flat Rate Envelope: 12 ½” (L) x 9 ½” (W)
- Priority Mail Flat Rate Legal Envelope: 15” (L) x 9 ½” (W)
- Priority Mail Flat Rate Padded Envelope 9 ½” (L) x 12 ½” (W)
All of the Priority Mail Flat Rate Envelopes are available with Priority Mail Flat Rate Express as well. These envelopes are perfect for documents, tickets, art, jewelry, and other non-bulky items. Aside from a few instances of shipping to closer zones, these envelopes will likely save you over weight-based Priority Mail shipping options.
Learn more about USPS zones in our blog – What Are USPS Zones and & How Do They Affect My Shipping?
USPS Priority Mail® Flat Rate Small Box
For smaller items, particularly small dense/heavy items that don’t fit in envelopes, the USPS Priority Mail Flat Rate Small Box is a great option. The dimensions for USPS Flat Rate Small Boxes are:
- Outside: 8 11/16″ x 5 7/16″ x 1 3/4″
- Inside: 8 5/8″ x 5 3/8″ x 1 5/8″
USPS describes the box size as about the same as three stacked DVD cases (imagine your three favorite movies to really drive this example home). For example, our customer Furls Fiberarts uses Flat Rate Small Boxes to ship their custom crochet and knitting needles. The boxes have self-adhesive flaps, and these folds have to be able to fully close. This box type is great for bulkier jewelry, small electronics, and more. This all comes back to the no bulging rule we mentioned earlier, and that’ll be the case for the rest of the boxes we discuss in this blog as well.
Join Furls Fiberarts and make Shipping Easy starting today.
USPS Priority Mail® Flat Rate Medium Box
Next up, we have the USPS Flat Rate Medium Boxes. The big difference between these boxes and the USPS Flat Rate Small Boxes is there are two different versions of the latter. The USPS Flat Rate Medium Boxes come in a side-loading version, which is a bit more narrow, and a top-loading version, which offers a bit more inside space.
USPS Flat Rate Medium Box-1 Specs (top-loading):
- Outside: 11 1/4″ x 8 3/4″ x 6″
- Inside: 11″ x 8 1/2″ x 5 1/2″
USPS Flat Rate Medium Box-2 Specs (side-loading):
- Outside: 14″ x 12″ x 3 1/2″
- Inside: 13 5/8″ x 11 7/8″ x 3 3/8″
As you can see, each box can lend itself to different types of products, but they each cost the same amount to ship. For example, Box 1 could be used to ship shoes, and Box 2 is what we use when we ship dozens of printed versions of ebooks to our partners.
As you start moving through the different Flat Rate Box sizes, we recommend to still compare their costs to other weight-based shipping options. There are still some instances where weight-based shipping would be cheaper than flat-rate shipping depending on weight and destination. Don’t be afraid to use your ShippingEasy rate calculator!
For more information on Priority Mail, you can read USPS Priority Mail: A Full Breakdown!
USPS Priority Mail Flat Rate Large Box
The USPS Flat Rate Large Box is really going to come in handy when you’re shipping larger, heavier packages; it’s going to be cheaper than weight-based options for packages weighing more than 25 pounds to most zones, even when it comes to those further zones. For scale, these boxes could be used to ship larger electronics like computers and laptops.
USPS Flat Rate Box Sizes – Large
- Outside: 12 1/4″ x 12 1/4″ x 6″
- Inside: 12″ x 12″ x 5 1/2″
A benefit of using a technology like ShippingEasy is that you can set rules for assigning shipping selections. If you have larger items that travel varying distances, you can set rules to select either USPS Flat Rate Large Box or USPS Priority Mail service to automate making the better decision based on weight and distance traveled!
ShippingEasy makes automation, well, easy. Find out how with your 30-day free trial today!
USPS Priority Mail APO/FPO/DPO Large Flat Rate Box
This package type is specifically used for sending items to troops and military personnel stationed overseas. It has the same dimensions and 70-pound limit as the USPS Flat Rate Large Box but includes a message of support for military troops and offers a discounted postage rate for the shipping service. Shipping overseas can be expensive, so this flat-rate shipping option makes it much easier to send items to loved ones.
USPS Flat Rate Box Sizes – APO/FPO/DPO
- Outside: 12 1/4″ x 12 1/4″ x 6″
- Inside: 12″ x 12″ x 5 1/2″
What is USPS Regional Rate shipping?
USPS Regional Rate is a variation of USPS Priority Mail Flat Rate, and it provides you with a flat rate of up to 15 or 20 pounds, depending on which of the two box options you use. The difference between this shipping method and USPS Priority Mail Flat Rate is Regional Rate still takes distance traveled into account whereas USPS Flat Rate doesn’t.
If you compare Regional Rate to both standard Priority Mail weight-based methods and other Priority Mail Flat Rate services, there are pros and cons. However, the savings can be substantial when it does win out, so it’s worth making the comparisons.
For example, if you compare Regional Rate Box A versus Medium & Large Flat Rate Boxes, Box A wins out for almost every Zone (up to 15 pounds).
When comparing Regional Rate Box B versus Medium & Large Flat Rate Boxes up to 20 pounds, Regional Rate Box B wins from Zones 1-5, but 6-7 Medium Flat Rate wins, and for Zones 8-9 Large Flat Rate wins.
Much like USPS Priority Mail Medium Flat Rate Boxes, there are two different versions of the Regional Rate Shipping Boxes for both A and B sizes.
USPS Priority Mail Regional Rate A1 dimensions:
- Outside: 10-1/8″(L) x 7-1/8″(W) x 5″(H)
- Inside: 10″(L) x 7″(W) x 4-3/4″(H)
- Opens from the top
USPS Priority Mail Regional Rate A2 dimensions:
- Outside Dimensions 13-1/16″(L) x 11-1/16″(W) x 2-1/2″(H)
- Inside Dimensions 12-13/16″(L) x 10-15/16″(W) x 2-3/8″(H)
- Opens from the top
USPS Priority Mail Regional Rate B1 dimensions:
- Outside: 12-1/4″(L) x 10-1/2″(W) x 5-1/2″(H)
- Inside: 12-1/8″(L) x 10-3/8″(W) x 5-1/4″(H)
- Opens from the top
USPS Priority Mail Regional Rate B2 dimensions:
- Outside: 15″(L) x 12″(W) x 3″(H)
- Inside: 14 3/4″(L) x 11 7/8″(W) x 2 7/8″(H)
- Opens from the top
Unbox the mystery of Regional Rate boxes in our blog.
When should you use Flat Rate shipping?
There are times when one method will be cheaper than another, so it’s still worth comparing your Flat Rate options with other USPS services to get the best rate for your small business. As we mentioned earlier, don’t be afraid to bust out the rate calculator in your ShippingEasy account. It’s there to be used!
Do USPS Flat Rate shipments come with a tracking number?
When you print a Flat Rate shipping label, it comes with the USPS tracking that USPS Priority Mail and Priority Mail Express packages traditionally include. The tracking number can also be automatically sent to your customer, so you can both keep track of your shipment in transit. Our free Branded Tracking also lets you customize the experience (emails, SMS updates, and a branded landing page) for your customers, rather than sending them to a carrier’s website to get package updates.
How can ShippingEasy help automate my packaging choices?
Do you wish you could assign specific packaging to your orders automatically? Well, you’re in luck! Through custom package options and Shipping Rules, you can automate your shipping process so that your preferred services and packaging are automatically applied to your orders. Pretty cool, huh?
Make Shipping Easy with your 30-day free trial today.
Baillee Perkins
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