To find the dimensions for USPS flat rate boxes, you’ll need to visit the United States Postal Service (USPS) website. Flat rate boxes are a convenient shipping option that allows you to send packages for a fixed price, regardless of the package’s weight. USPS offers various sizes of flat rate boxes to accommodate different types of items.

Here’s a step-by-step guide on how to find the dimensions for these boxes:

  • 1. Go to the USPS website: Open your preferred web browser and navigate to the official USPS website at
  • 2. Locate the “Quick Tools” menu: On the USPS homepage, you’ll find a menu labeled “Quick Tools” near the top left corner of the page. Hover your cursor over this menu to reveal a dropdown list of options.
  • 3. Click on “Calculate a Price”: From the “Quick Tools” dropdown menu, click on the “Calculate a Price” option. This will take you to the “Calculate Postage” page.
  • 4. Scroll down to the “Flat Rate” section: On the “Calculate Postage” page, scroll down until you find the section titled “Flat Rate.” This section provides an overview of the flat rate shipping options available through USPS.
  • 5. Click on “See Flat Rate Boxes”: Within the “Flat Rate” section, you’ll find a link that says “See Flat Rate Boxes.” Click on this link to view the various flat rate box sizes and their corresponding dimensions.
  • 6. Review the flat rate box dimensions: On the “Flat Rate Boxes” page, you’ll see a list of available flat rate box sizes, along with their dimensions (length, width, and height) in inches. The list includes:
    • Small Flat Rate Box: 8 11/16″ x 5 7/16″ x 1 3/4″
    • Medium Flat Rate Box (Top Loading): 11 1/4″ x 8 3/4″ x 6″
    • Medium Flat Rate Box (Side Loading): 14″ x 12″ x 3 1/2″
    • Large Flat Rate Box: 12 1/4″ x 12 1/4″ x 6″
    • APO/FPO/DPO Large Flat Rate Box: 12 1/4″ x 12 1/4″ x 6″
    • Large Flat Rate Board Game Box: 23 11/16″ x 11 3/4″ x 3″

By following these steps, you can easily find the dimensions for USPS flat rate boxes. This information will help you determine the most suitable box size for your shipping needs, ensuring that your package arrives safely and securely at its destination.

Additional resources

Another relevant government resource is the Federal Register, which publishes official rules and regulations related to the USPS, including updates on postal services and shipping standards. The Code of Federal Regulations (CFR) also contains information on postal services, specifically in Title 39, which covers the United States Postal Service and the Postal Regulatory Commission.

Furthermore, the United States Government Publishing Office (GPO) provides access to various publications and resources related to USPS, including the Domestic Mail Manual (DMM), which contains mailing standards and guidelines for domestic mail services. The DMM can be a valuable resource for understanding the requirements and dimensions for USPS flat rate boxes.

Lastly, the Postal Regulatory Commission (PRC) is an independent agency that oversees the USPS and ensures transparency and accountability in postal services. The PRC website offers reports, data, and other resources related to postal services, which can be helpful in understanding the dimensions and guidelines for USPS flat rate boxes.

Our articles make government information more accessible. Please consult a qualified professional for financial, legal, or health advice specific to your circumstances.

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