
The US Postal Service (USPS) offers a variety of Priority Mail box sizes to fit your shipping needs. The most common sizes are the 8.5 x 12 x 6 inches, 10 x 13 x 5 inches, and 12 x 12 x 6 inches.
Each size has its own unique dimensions, making it perfect for shipping packages of different shapes and sizes. For example, the 8.5 x 12 x 6 inches box is ideal for shipping small to medium-sized items.
The USPS Priority Mail box sizes are designed to be durable and easy to use. The 10 x 13 x 5 inches box is a great option for shipping larger items that need extra protection.
To ensure accurate shipping rates and delivery times, it's essential to choose the right box size for your package.
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USPS Priority Mail Box Sizes
USPS Priority Mail box sizes are available in various dimensions to fit your shipping needs.
The smallest box size is 8-5/8" x 5-3/8" x 1-5/8" and is perfect for shipping stacked DVD cases, jewelry, and electronic items.
The medium-sized box comes in two options: 11" x 8-1/2" x 5-1/2" and 13-5/8" x 11-7/8" x 3-3/8". These boxes are ideal for shipping shoes and garments.
The large box size is 12" x 12" x 5-1/2" and is great for shipping computers, gifts, books, and other heavier items.
You can also use the Priority Mail Express box, which comes in three sizes: 12-1/2" x 9-1/2" x 3-1/2", 10" x 7" x 4", and 15-5/8" x 12-7/8" x 2-5/8".
Here are the internal and external dimensions of the USPS Priority Mail box sizes:
Knowing the right box size can help you save money on shipping costs.
Shipping Options
When shipping with USPS Priority Mail, you have several options to choose from.
USPS offers a variety of shipping options, including Priority Mail, Priority Mail Express, and First Class Package Service.
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The size and weight of your package will determine which shipping option is best for you.
USPS Priority Mail is a cost-effective option for packages up to 70 pounds and 130 inches in length and girth combined.
Priority Mail Express is a faster option that guarantees delivery within 1-3 business days, depending on the destination.
First Class Package Service is a budget-friendly option for lightweight packages, weighing 15 ounces or less.
It's essential to check the USPS website for the most up-to-date pricing and shipping times.
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Size Variations
The size variations of USPS Priority Mail boxes can be a bit confusing, but don't worry, I've got you covered. There are different sizes available, each with its own dimensions and uses.
The small flat rate box measures 8 11/16″ x 5 7/16″ x 1 3/4″, making it perfect for shipping small items like jewelry, electronics, or event tickets. This box has a 70 lb weight limit for domestic shipments and a 4 lb weight limit for international shipments.
The medium flat rate box comes in two sizes, 11 1/4″ x 8 3/4″ x 6″ and 13.5″ x 11.5″ x 3″, making it ideal for shipping bigger items like clothes, toys, and household goods. These boxes have the same shipping cost, making it easy to budget your shipping costs.
Here's a comparison of the two medium flat rate box sizes:
The large flat rate box measures 12 1/4″ x 12 1/4″ x 6″, making it perfect for shipping large items. However, it's essential to compare the costs of flat-rate shipping with weight-based shipping options, as there may be instances where weight-based shipping is cheaper.
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Choosing the Right for Your Needs
Choosing the right USPS Priority Mail box size is crucial for a smooth shipping process.
Consider your item's weight and dimensions to pick the right box.
Think about where your item is going and how fast you need it to arrive.
Prices for USPS Priority Mail boxes start at $8.45 for small boxes.
USPS padded flat rate envelope dimensions are great for shipping fragile or odd-shaped items.
Here are some key factors to consider when picking a Priority Mail box:
- Item weight and dimensions
- Destination and shipping speed
- Cost-effectiveness of Flat Rate options
- Special considerations for fragile or oversized items
Envelope Sizes
USPS Priority Mail offers a range of flat rate envelopes that are perfect for shipping documents, tickets, art, jewelry, and other non-bulky items.
There are three types of flat rate envelopes available: the Priority Mail Flat Rate Envelope, the Priority Mail Flat Rate Legal Envelope, and the Priority Mail Flat Rate Padded Envelope.
The dimensions of these envelopes are specific: the Priority Mail Flat Rate Envelope is 12 ½” (L) x 9 ½” (W), the Priority Mail Flat Rate Legal Envelope is 15” (L) x 9 ½” (W), and the Priority Mail Flat Rate Padded Envelope is 9 ½” (L) x 12 ½” (W).
All of these envelopes are also available with Priority Mail Flat Rate Express.
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The standard size of a flat rate envelope is 12.5″ x 9.5″.
Here are the dimensions of the three types of flat rate envelopes:
Note that the Priority Mail Flat Rate Envelope has a 70 lb weight limit for domestic shipments and a 4 lb weight limit for international shipments.
APO/FPO/DPO Boxes
APO/FPO/DPO Boxes offer a discounted postage rate for shipping overseas, making it easier to send items to loved ones. This is particularly useful for sending items to troops and military personnel stationed overseas.
The USPS Priority Mail APO/FPO/DPO Large Flat Rate Box has the same dimensions as the USPS Flat Rate Large Box, but with a discounted postage rate for shipping overseas. It includes a message of support for military troops.
Shipping overseas can be expensive, so this flat-rate shipping option makes a big difference. The 70-pound limit of the APO/FPO/DPO Large Flat Rate Box provides ample space for sending items to troops and military personnel.
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Postage and Express

Priority Mail Express is a guaranteed delivery service that offers overnight scheduled delivery by 10:30 am to most US addresses with a few exceptions.
The flat rate for Priority Mail Express starts at $24.70 with 3 box types meant for different types of items. You can get these boxes without any charges from USPS post offices near you or you can also order them online, and get a free delivery to your address too.
Priority Mail is a standard delivery service by USPS, which usually delivers packages and envelopes in 1-3 days. The flat rate boxes for this service start at $6.70 at the post offices, and the commercial prices for the same start at $6.55.
You can choose from a variety of flat rate boxes, including the Small Flat Rate Box, which costs $7.20 for Post Office Rates and $7.05 for Commercial Rates. Another option is the Medium Flat Rate Box, which costs $13.65 for Post Office Rates and $12.85 for Commercial Rates.
Here's a comparison of the Post Office and Commercial Rates for some of the flat rate boxes:
Express Sizes for Shipping
You can get free Priority Mail Express boxes at USPS locations or order them online. These boxes are perfect for expedited shipping services that ensure overnight delivery to most locations in the United States.
The size of a Priority Mail Express box is 12-1/2" x 9-1/2" x 3-1/2". This is suitable for documents and small packages.
A slightly smaller box is also available, measuring 10" x 7" x 4". This is ideal for even smaller items.
A large-sized Priority Mail Express box has dimensions of 15-5/8" x 12-7/8" x 2-5/8". This is perfect for bigger items.
Here are the sizes of the Priority Mail Express boxes in a quick reference list:
- Small: 10" x 7" x 4"
- Medium: 12-1/2" x 9-1/2" x 3-1/2"
- Large: 15-5/8" x 12-7/8" x 2-5/8"
These sizes will help you choose the right box for your shipping needs.
Express
Express services are available from USPS, offering guaranteed delivery options.
Priority Mail Express provides overnight scheduled delivery by 10:30 am to most US addresses, with a few exceptions.
The flat rate boxes for Priority Mail Express start at $24.70, with three box types for different types of items.

This service is available with a maximum allowed weight per box of 70 lbs.
You can get these boxes without any charges from USPS post offices near you, or order them online with free delivery.
The shipping prices of these boxes are determined by the type of box, not their weights.
For example, the large flat rate box costs $17.65, while the small flat rate box costs $7.05, and you can still ship products up to 70 lbs. in them.
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Postage
Postage can be a complex and confusing topic, but don't worry, I've got you covered.
USPS offers two types of pricing for their flat rate boxes: Post Office Rates and Commercial Rates. Commercial rates are slightly lesser than the post office rates, but you require a minimum of 50 parcels for the commercial pricing by USPS.
You can also use alternative services like EasyPost and Stamps.com for commercial and discounted rates of these boxes. These technology-based companies provide an economical and convenient way of printing USPS postage paid shipping labels.
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If you're looking for a specific type of flat rate box, USPS offers a wide range of options, including the Priority Mail Express Flat Rate Envelope, Priority Mail Flat Rate Envelope, and Priority Mail Large Flat Rate Box.
Here's a breakdown of the Post Office and Commercial Rate Sheets for USPS Flat Rate Boxes:
EasyPost and Stamps.com are two of the premiere online vendors of USPS Postage, and they can help you save money on your postage costs.
Frequently Asked Questions
What priority mail box is 7x7x6?
The 7x7x6 box is a USPS Priority branded box, specifically designed for use with the USPS Priority mail package service.
Is USPS discontinuing priority mail boxes?
Yes, USPS is discontinuing Priority Mail Regional Rate Boxes A and B, effective January 22, 2023. Check our website for alternative shipping options and pricing.
Are priority mail boxes still free?
Yes, Priority Mail boxes are still free from the USPS, but be aware that some services have changed, including the discontinuation of USPS Regional Rate.
What size is a USPS large priority box?
A USPS Large Priority Box measures 12 inches long, 12 1/4 inches wide, and 6 inches high. This size is ideal for shipping larger items, such as gifts or packages, at a flat rate.
Sources
- https://www.customproductpackaging.com/blog/priority-mail-box-sizes-how-to-choose-the-right-one
- https://uspsprioritymailboxes.com/usps-priority-mail-box-sizes/
- https://shippingeasy.com/blog/what-are-usps-flat-rate-boxes/
- https://support.ordoro.com/how-to-pick-your-usps-box-type/
- https://elextensions.com/usps-flat-rate-boxes-prices-and-sizes-woocommerce-shipping/
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