USPS 6×9 Envelope (Cost to Ship, Does It Count as a Letter + Other FAQs)

You may not realize it, but envelopes come in a whole lot of sizes and shapes. This variety is useful in making sure you always have the right envelope to fit your mail, but it can also make knowing how much you need to pay tricky.

In this article, we’re looking at one specific envelope- the 6×9 size. How does USPS classify this envelope size? If you’d like to find out, keep reading!

How Does USPS Ship 6×9 Envelopes In [currentyear]?

USPS considers 6×9 envelopes as letters because they fall within the acceptable dimensions for letters in [currentyear]. 6×9 envelopes (including manila envelopes and some bubble mailers) weighing 1 ounce or less can be mailed using 1 Forever Stamp. Each additional ounce is priced at $0.20. Bubble mailers thicker than ¾ inch are considered packages and are priced accordingly.

We’ve got a lot more information to share about 6×9 envelopes, so make sure you keep reading for useful facts and tips regarding this subject!

Is a 6×9 Envelope Considered a Letter?

A 6×9 envelope is considered a letter because its dimensions fall within USPS’ guidelines for letter sizes.

These guidelines state that a letter must be:

  • Rectangular
  • At least 3 ½ inches high x 5 inches long x 0.007 inches thick
  • No more than 6 ⅛ inches high x 11 ½ inches long x ¼ inch thick

Because 6×9 envelopes meet all of these criteria, the Postal Service considers them letters and prices them as such.

How Much Do 6×9 Envelopes Cost?

How Much Do 6x9 Envelopes Cost? USPS

Postage rates for 6×9 envelopes depend on the mail class a customer selects.

In most cases, a 6×9 envelope weighing up to 1 ounce will be mailed as a First-Class letter.

Such letters require 1 First-Class stamp (also known as a Forever Stamp). Forever Stamps are currently priced at $0.58.

If a 6×9 envelope weighs more than 1 ounce, it can still be sent through the First-Class Mail service, but extra postage will be required.

Each additional ounce costs the sender $0.20.

Therefore, if a 6×9 envelope weighs between 1.1 and 2.0 ounces, it will cost $0.78 to send at the current rate.

If the envelope weighs between 2.1 and 3 ounces, it will cost $0.98.

If the envelope weighs between 3.1 and 3.5 ounces, it will cost $1.18 to mail.

Above 3.5 ounces (and/or ¼ inch thickness), a 6×9 envelope will no longer be considered a letter, but rather a large envelope.

Large envelopes (also called Flats) have a different pricing structure as shown below.

Weight Not Over (Oz.) Price
1 $1.16
2 $1.36
3 $1.56

How Much Does It Cost to Mail a 6×9 Bubble Mailer?

Postage for 6×9 bubble mailers depends on the thickness of the mailer.

If a bubble mailer is a ¾ inch thick or less when filled, it is considered an envelope. In that case, you can follow the letter pricing guidelines for 6×9 envelopes detailed above.

If a bubble mailer is thicker than ¾ inch, it’s considered a package and is priced accordingly. Most bubble mailers fall into this category.

When sending bubble mailers as packages, customers can choose the service they want to use. USPS First-Class and Priority Mail are the most popular services.

First-Class is a good option if your bubble mailer weighs less than 13 ounces.

First-Class prices start at $4.50 for light packages traveling locally and go up to $7.65 for 13-ounce packages traveling across the country.

Select Priority Mail if your item weighs more than 13 ounces and/or if you want faster delivery.

A padded Flat Rate envelope starts at $9.65.

How Many Stamps Do I Need for a 6×9 Manilla Envelope?

Smaller manila envelopes, such as those measuring 6×9, meet the size requirements for standard letter mail.

They can be shipped with 1 Forever Stamp as long as the weight does not exceed 1 ounce.

As with other types of 6×9 envelopes, each additional ounce of postage costs $0.20, up to a maximum weight of 3.5 ounces.

To learn more, you can also read our posts on 14 USPS stamp types, how many stamps do you need for a manila envelope, and USPS flat rate envelope restrictions.


In most cases, USPS considers 6×9 envelopes as standard letters and prices them as such. This means you can pay for your postage using a Forever Stamp (and additional ounce stamps if necessary).

Exceptions to this rule are 6×9 envelopes weighing more than 3.5 ounces and 6×9 bubble mailers thicker than ¾ inch.

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Marques Thomas

Marques Thomas graduated with a MBA in 2011. Since then, Marques has worked in the retail and consumer service industry as a manager, advisor, and marketer. Marques is also the head writer and founder of

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