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Forever Stamp: Some tips to help you find stamps that fit your envelope size

Pete Seeger Stamps – 2022 USPS Forever Stamp

Forever Stamp: Some tips to help you find stamps that fit your envelope size

I wonder if you have such a question when you want to send a letter: How big should my envelope be? How much will it cost? What size letter does the forever stamp cover? How many stamps are needed to get the letter to its destination? Here is some knowledge about the sizes of forever stamps and envelopes. After reading this article, your questions will be answered.


What are the sizes, formats, and shapes of Forever stamps issued by the USPS?

There are generally three shapes for the stamps issued: Rectangle, Square, and Round. Although they are all postage stamps, the different shapes and sizes indicate that their uses are not exactly the same.

halloween theme Day Of The Dead FOREVER Stamps
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Rectangular Forever Stamps

Rectangular stamps are the most common shape. They range in size from 0.870″ W x 0.98″ H to 1.255″ W x 1.59″ H. Depending on the actual size, specific rectangular sizes range from forever to jumbo. For a standard-size rectangular envelope weighing one ounce, an ordinary eternity stamp is usually sufficient. If you want to convey more information, a large envelope requires two first-class stamps for the first two ounces and then another $0.15 postage for each additional ounce.

Colorado Hairstreak Stamps(99¢ Non-Machineable For Square Envelopes)
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Square Forever Stamps

Square Forever stamps are primarily used in select designs, including the Music Icons® series of stamps and the Total Eclipse of the Sun stamp. The 2022 release of the Folk Music Legend Pete Seeger Commemorative U.S. Stamp is part of the Music Icons® collection.

Square stamp designs are also used on stamps with unique rates, such as those designed for square, non-workable envelopes. Square stamps generally start at $0.99 and are usually used for special square envelopes such as wedding invitations.

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Round Forever Stamps

A Ball stamp, issued May 16, 2017, features a round stamp shape for the first time! The most common round stamps on the market now are international stamps. The international forever stamps have a circular border and always have the words “Global” and “Forever” to distinguish them from other forever stamps.

Have A Ball Stamps – 2017 USPS Forever Stamps
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Stamps sold in three formats

Stamps are sold in different formats. A slab is a sheet of stamps cut from the original sheet, including 20 stamps that cost $12. Coils are strips of stamps sold in rolls (one stamp wide) that contain 20-1000 stamps and range in price from $12 to $6000. This is the first option when it comes to some business needs. Stamp booklets are the simplest option to carry around. They usually contain 20 stamps, mostly for postal stamps.

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How many sizes of envelopes are there?

The size of an envelope is determined by its purpose. Generally, there are three types of envelopes: Business, Booklet, and Catalog envelopes. They come in many different sizes as the below table shows.

Business envelope

Business envelopes are widely used for direct mail and transactional mail (for example, monthly statements or bills).

Common Envelope Name

Standard Size

Maximum Enclosure

6-1/4 envelope

3.5 x 6 inches

3.25 x 5.75 inches

6-3/4 envelope

3.625 x 6.5 inches

3.375 x 6.25 inches

7 envelope

3.75 x 6.75 inches

3.5 x 6.5 inches

8-5/8 envelope

3.625 x 8.625 inches

3.375 x 8.375 inches

9 envelope

3.875 x 8.875 inches

3.625 x 8.625 inches

10 envelope

4.125 x 9.5 inches

3.875 x 9.25 inches

11 envelope

4.5 x 10.375 inches

4.25 x 10.125 inches

12 envelope

4.75 x 11 inches

4.5 x 10.75 inches

14 envelope

5 x 11.5 inches

4.75 x 11.25 inches

Booklet Envelopes Sizes

Booklet envelopes are open-sided, double-stitched envelopes that come in a variety of standard sizes.

Common Envelope Name

Standard Size

Maximum Enclosure

6 envelope

5.75 x 8.875 inches

5.5 x 8.625 inches

6-1/2 envelope

6 x 9 inches

5.75 x 8.75 inches

6-5/8 envelope

6 x 9.5 inches

5.75 x 9.25 inches

9 envelope

8.75 x 11.5 inches

8.5 x 11.25 inches

9-1/2 envelope

9 x 12 inches

8.75 x 11.75 inches

10 envelope

9.5 x 12.625 inches

9.25 x 12.375 inches

Catalog Envelopes Sizes

Catalog envelopes are open center-sewn or single-sewn envelopes with a flap over the short dimension. They are usually used for policies and/or insurance information that should not be folded.

Common Envelope Name

Standard Size

Maximum Enclosure

6 x 9 envelope

6 x 9 inches

5.75 x 8.75 inches

9 x 12 envelope

9 x 12 inches

8.75 x 11.75 inches

10 x 13 envelope

10 x 13 inches

9.75 x 12.75 inches


How many stamps are needed for different-sized envelopes?

Most people want to know what size envelopes require extra postage. Generally, postage is determined by three main factors: the weight, the shape, and the size of the envelope. Some oversized and overweight envelopes may require extra postage due to the extra service needed to be done by postal machines to sort the mail. For example, square envelopes require additional postage. If your envelope is 3.5 inches or less in height, 5 inches or less in length, and 0.007 inches or less in thickness. Then simply use a forever stamp. If you are mailing a standard-size envelope weighing less than one ounce, you will only need one forever stamp or current postage.

For any domestic or international mail weighing more than one ounce, you must include additional postage with the forever stamp to ensure delivery by the USPS. You may also purchase higher denomination stamps to increase postage.

But forever stamps do not have to be used for all mail, such as postcards. There are special postcard stamps available for purchase that are cheaper than forever stamps. However, this only applies if your postcard has a standard format. If it has a super-size, you still need to use enough stamps.

However, the most important thing is not the size, but the weight. So, please weigh the envelopes before you stamp them because heavier letters will be returned for lack of postage.

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