USPS Flat Rate: Sizes, Prices, and Shipping Tips

USPS Flat Rate
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USPS Flat Rate Shipping: Box Sizes, Prices, and How It Works

Shipping can be one of the more complex aspects of running a business or managing personal shipments. The United States Postal Service (USPS) offers a variety of shipping options designed to simplify the process and reduce costs. One of the most popular options is the USPS Flat Rate shipping service. This guide will provide an in-depth look at USPS Flat Rate box sizes, prices, and how this service works, helping you determine if it's the right choice for your shipping needs.

What is USPS Flat Rate Shipping?

USPS Flat Rate shipping is a service that allows you to send packages at a fixed price, regardless of the package's weight or destination within the United States. The premise is simple: if it fits, it ships. You can pack any items that fit into the provided USPS Flat Rate boxes or envelopes, and the price will remain the same, making budgeting for shipping straightforward and predictable.

Benefits of USPS Flat Rate Shipping

  • Simplicity: No need to weigh packages if they fit within the dimensions of the box.

  • Cost-Effectiveness: Especially beneficial for heavier items that would be costly to ship based on weight.

  • Speed: Flat Rate packages are delivered within 1-3 business days with tracking and delivery updates.

  • Availability: Includes free package pickup service at your home or office.

USPS Flat Rate Box Sizes and Prices

USPS Flat Rate shipping offers a convenient way to send packages at a fixed cost, regardless of weight or destination within the United States. Here's a more detailed breakdown of the various sizes and prices of USPS Flat Rate boxes and envelopes, designed to meet a variety of shipping needs:

1. Flat Rate Envelopes

Ideal for documents and other flat items, these envelopes are a cost-effective choice for nationwide shipping.

  • Regular Envelope: Measures 12 1/2" x 9 1/2". Perfect for papers, cards, and any flat items that fit within these dimensions.

  • Padded Envelope: Also measures 12 1/2" x 9 1/2", but offers padding to protect items that need a bit more cushioning during transit.

  • Legal Envelope: Slightly larger at 15" x 9 1/2", suitable for legal documents and slightly bulkier materials.

  • Price: Costs start at $8.95, varying slightly based on the type of envelope and the specific contents’ protection needs.

2. Small Flat Rate Box

A compact option for small, dense items that require sturdy packaging.

  • Dimensions: 8 11/16" x 5 7/16" x 1 3/4". This box is ideal for small electronic devices, books, or chocolates.

  • Price: $9.45. An affordable choice for items that are heavy relative to their size.

3. Medium Flat Rate Boxes

Offered in two shapes to accommodate different types of contents, making them versatile for a broad range of items.

  • Type 1 Dimensions: 11 1/4" x 8 3/4" x 6". Best suited for small to medium-sized items that are too large for the small flat rate box.

  • Type 2 Dimensions: 14" x 12" x 3 1/2". This flatter version is excellent for clothing, board games, or books.

  • Price: Both types are priced at $16.10, providing a middle-ground option between the small and large flat rate boxes.

4. Large Flat Rate Box

Designed for larger items or multiple gifts that can be packed together.

  • Dimensions: 12 1/4" x 12 1/4" x 6". Ideal for sending larger items such as computer hardware, shoes, or a significant quantity of clothing.

  • Price: $21.50. While it’s the most expensive flat rate option, it’s cost-effective for sending heavy items across long distances.

5. APO/FPO/DPO Flat Rate Box

Specially priced for sending items to U.S. military members stationed abroad, matching the dimensions of the large flat rate box.

  • Dimensions: 12 1/4" x 12 1/4" x 6". This box is similar to the large flat rate box but comes with a discount as a gesture of goodwill towards the military.

  • Special Price: $20.00. This reduced rate applies when shipping to Army Post Office (APO), Fleet Post Office (FPO), or Diplomatic Post Office (DPO) locations.

How It Works

To use USPS Flat Rate shipping:

  1. Choose a Box or Envelope: Select the Flat Rate box or envelope that best fits your items without modifying the container.

  2. Pack Your Items: Securely pack your items within the box. You can include anything as long as it fits without altering the shape of the box.

  3. Label and Ship: Seal your box and label it with the appropriate shipping information. You can drop it off at a USPS location or schedule a pickup.

Is Priority Mail the Same as Flat Rate?

USPS Priority Mail is a versatile shipping service that offers several options to cater to various shipping needs. These include Priority Mail Flat Rate, Priority Mail weight-based, and Priority Mail Cubic. The commonality among these is the service level — Priority Mail, which ensures delivery within 1-3 business days depending on the destination.

Priority Mail Flat Rate is a subset of Priority Mail, offering a fixed cost shipping solution regardless of the weight or distance (as long as the package weighs less than 70 lbs and fits within the provided packaging). Conversely, Priority Mail weight-based pricing varies based on the weight of the package and the distance it travels.

Which is Cheaper: Flat Rate or Priority Mail?

The cost-effectiveness of Flat Rate versus weight-based Priority Mail depends on the specifics of the shipment:

  • Flat Rate is typically more economical for heavy items traveling long distances.

  • Weight-based Priority Mail may be more cost-effective for lighter packages traveling shorter distances.

When to Use USPS Flat Rate Envelopes

Flat Rate Envelopes are almost always the cheapest option when shipping documents or small items that can fit into an envelope. However, there are exceptions:

  • Use your own envelope if the package weighs exactly 1 lb and is traveling locally. It's likely cheaper.

  • For items under 1 lb, consider using your own envelope and shipping via USPS First-Class Package Service, which is generally less expensive for light packages.

When to Use USPS Flat Rate Boxes

Flat Rate Boxes are ideal under specific conditions:

  • For packages weighing between 1 and 20 lbs, choose Flat Rate for longer distances as it tends to be cheaper.

  • For items under 1 lb or over 20 lbs, it's often more cost-effective to use your own packaging and select another USPS service suitable for the weight and distance.

Here are some specific scenarios where using your own box is cheaper than a Flat Rate box, based on USPS pricing:

  • Small Flat Rate Box (8 11/16" x 5 7/16" x 1 3/4"): If the package weighs 2 lbs and is traveling 500 miles, it's cheaper to use your own packaging.

  • Medium Flat Rate Box (11 1/4" x 8 3/4" x 6"): For a 1 lb package traveling 2,000 miles, using your own box saves nearly $5.

  • Large Flat Rate Box (12 1/4" x 12 1/4" x 6"): For a 0.5-1 lb package traveling to Zone 8, significant savings can be achieved with your own packaging.

Is Priority Mail (Weight-based) or Flat Rate Faster?

Both Flat Rate and weight-based Priority Mail options are part of the Priority Mail stream, ensuring that packages are delivered within the same time frame of 1-3 business days. The choice between these options should therefore be based on cost-efficiency rather than speed.

Other Considerations and Restrictions

It’s important to be aware of USPS restrictions on mailing hazardous, restricted, and prohibited items. This includes items like explosives, flammable objects, and certain chemicals. For detailed guidance, always refer to the USPS Shipping Restrictions page.

How to Get a USPS Priority Mail Flat Rate Label

Creating a shipping label for your Priority Mail Flat Rate package can be done quickly through online platforms like Shippo. After setting up an account, you can print your label and either drop off the package at a USPS facility or schedule a pickup.


USPS Flat Rate shipping is an excellent solution for anyone looking for an easy, predictable, and often economical way to send packages across the country. Whether you’re shipping books, metals, or other heavy items, the Flat Rate service can accommodate your needs without the hassle of weighing items or calculating varying costs. By understanding the different sizes and how the service works, you can efficiently manage your shipping requirements and keep your expenses in check.

USPS Priority Mail and Flat Rate Shipping (FAQs)

1. What is the difference between USPS Priority Mail and Priority Mail Flat Rate?

  • USPS Priority Mail is a service that offers delivery within 1-3 business days based on the package’s weight, size, and travel distance. Priority Mail Flat Rate, on the other hand, offers a single rate for shipping packages up to 70 lbs in weight, regardless of where they are being sent within the United States, as long as they fit within the specified boxes or envelopes provided by USPS.

2. How do I decide whether to use Priority Mail Flat Rate or weight-based Priority Mail?

  • Choose Flat Rate when shipping heavier items over long distances as it tends to be more cost-effective. Use weight-based Priority Mail for lighter packages or when shipping over shorter distances, as it may be cheaper.

3. Are Flat Rate boxes free? Where can I get them?

  • Yes, USPS Flat Rate boxes are free. You can pick them up at your local Post Office or order them online from the USPS website, and they will be delivered to your address.

4. How long does it take for Priority Mail and Priority Mail Flat Rate to be delivered?

  • Both Priority Mail and Priority Mail Flat Rate services offer delivery within 1-3 business days, depending on the origin and destination of the package.

5. Can I use any box for Priority Mail Flat Rate shipping?

  • No, to qualify for Flat Rate pricing, you must use the specific boxes and envelopes provided by USPS for Flat Rate shipping. These are specially marked as Flat Rate.

6. What happens if my package weighs more than 70 lbs?

  • Packages exceeding 70 lbs do not qualify for Priority Mail or Priority Mail Flat Rate services. You will need to use another USPS service or a different carrier that can accommodate heavier shipments.

7. Is tracking included with Priority Mail and Priority Mail Flat Rate?

  • Yes, both services include tracking at no additional cost. You can track your shipment using the tracking number provided at the time of shipping.

8. Are there any items that cannot be shipped via Priority Mail or Priority Mail Flat Rate?

  • Yes, there are restrictions on hazardous, restricted, and prohibited items, such as explosives, airbags, ammunition, and gasoline, among others. Always check the USPS Shipping Restrictions page or consult with your local Post Office before shipping.

9. How do I create a shipping label for Priority Mail or Priority Mail Flat Rate?

  • You can create and print shipping labels through the USPS website, USPS Click-N-Ship service, or through third-party platforms like Shippo. After printing, attach the label to your package before mailing.

10. Can I schedule a pickup for my Priority Mail or Priority Mail Flat Rate package?

  • Yes, USPS offers free package pickup from your home or office for Priority Mail and Priority Mail Flat Rate packages. You can schedule a pickup through the USPS website when you create your shipping label or via your USPS account.

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