
To mail a 5.5 x 8.5 postcard, you'll need to follow the regulations set by the United States Postal Service (USPS). The USPS considers postcards to be a type of mailpiece that requires specific dimensions and content guidelines.
The USPS allows postcards to be up to 0.016 inches thick. This means you can use a standard postcard stock that meets this thickness requirement.
The 5.5 x 8.5 size is a popular choice for postcards, but it's essential to ensure your postcard meets the USPS's maximum size limit of 11.5 inches in length and 6 inches in height.
Related reading: Cost to Mail Postcard in Us
US Postal Service Regulations
The US Postal Service has specific regulations for mailing postcards, and it's essential to follow them to ensure your cards arrive safely and efficiently.
The US Postal Service requires that certain areas of the address side of the postcard be left white for addressing, postage, and bar coding. This includes background color, text, and any photos/images.
Curious to learn more? Check out: Express Mail Service Tracking India

If you're using a mailing service, the dimensions and exclusions vary based on the postcard size, so be sure to check the layouts for your specific size. You can find more information on USPS requirements by visiting your local post office or the official US Postal Service website.
The most commonly used postcard dimensions are:
- 3” x 4”
- 3.5” x 8.5”
- 4.25” x 5.5”
- 4” x 6” (the standard postcard size)
- 5” x 7”
- 5.5” x 8.5”
- 6” x 9”
- 6.5” x 9.5”
- 6” x 11”
The 5.5” x 8.5” postcard size is a popular choice for mailing, offering a good balance between space and simplicity.
Postcard Dimensions and Standards
Postcard dimensions can vary, but the most commonly used sizes are a good place to start when sending mail.
The standard postcard size is 4” x 6”, which is widely accepted and used by many mailers.
You'll also see 3” x 4” and 5” x 7” postcards, which are also popular choices.
The size of your postcard can affect the cost of mailing, so it's worth considering.
Here are some commonly used postcard dimensions:
- 3” x 4”
- 3.5” x 8.5”
- 4.25” x 5.5”
- 4” x 6”
- 5” x 7”
- 5.5” x 8.5”
- 6” x 9”
- 6.5” x 9.5”
- 6” x 11”
Frequently Asked Questions
What are USPS rules for postcards?
According to USPS regulations, postcards must be rectangular and measure between 3.5" x 5" and 6" x 9" in size. To qualify, they must also meet specific thickness requirements.
What size postcard requires extra postage?
Postcards larger than 6" x 11" require extra postage, including 8.5" x 11" and larger sizes, which are mailed as Flats.
Sources
- https://sharpdots.com/print/direct-mail-specifications/
- https://www.expresscopy.com/postcard-specifications
- https://www.printingforless.com/resources/usps-mail-layout-templates/
- https://vipparcel.com/blog/usps_postcard_mailing_guidelines_-_avoid_costly_mailing_mistakes
- https://printtobrand.com/postcard-sizes-dimension-guide/
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