Standard Sizes and Dimensions for Envelope Enclosures

Open side envelopes with square, often deep flaps and side seams, these envelopes - also called A-Style or A-Line -- can have deckle edges on the top flap and are often used with matching text and cover papers in white and colors. You may find ​the announcement and other envelopes called invitation, greeting card, or personal correspondence envelopes. Look at the size and flap/seam style to know exactly what style you're getting.

The following list shows the name/number designation, envelope dimensions, and approximate maximum enclosure dimensions for some of the more common sizes of the A-series envelope style. Actual dimensions for enclosures will depend on the thickness of the enclosure (paper thickness, number of pages).

A1 
5.125 x 3.625
4.75 x 3.5

A2 
5.75 x 4.375
5.5 x 4.125

A6 
6.5 x 4.75
6.25 x 4.5

A-7 
7.25 x 5.25
7 x 5

A8 
8.125 x 5.5
7.875 x 5.25

A-Long 
(Slimline)
8.875 x 3.875
8.625 x 3.625

A10 
9.5 x 6
9.25 x 5.75

All measurements in inches: .125 = 1/8 | .25 = 1/4 | .375 = 3/8 | .5 = 1/2 | .625 = 5/8 | .875 = 7/8
These A series envelope sizes apply specifically to the United States. Standard International envelope sizes differ.

Used for formal invitations, greeting cards, and some stationery, Baronial is an open side, almost square envelope with pointed flaps and diagonal seams.

Inner/Outer envelope sets come with the (slightly smaller) inner envelope ungummed.

The following list shows the name/number designation, envelope dimensions, and approximate maximum enclosure dimensions for some of the more common sizes of this envelope style. Actual dimensions for enclosures will depend on the thickness of the enclosure (paper thickness, number of pages).

2
4.25 x 3.1875
4 x 2.9375

4
5.125 x 3.625
4.875 x 3.375

5
5.625 x 4.125
5.375 x 3.875

5 ¼
5.25 x 4.25
5 x 4

5 ½ 
5.625 x 4.375
5.375 x 4.125

6
6.5 x 4.75
6.25 x 4.625

Gladstone 
5.5625 x 3.5625
5.375 x 3.375

Astor
5.625 x 3.625
5.375 x 3.5

Lee 
7.25 x 5.25
7 x 5.125

All measurements in inches: .125 = 1/8 | .25 = 1/4 | .375 = 3/8 | .5 = 1/2 | .625 = 5/8 | .875 = 7/8
These Baronial envelope sizes apply specifically to the United States. Standard International envelope sizes differ.

Open side envelopes with small square or wallet flaps and side seams, booklet envelopes are ideal for overall printing and mailing.

Booklet envelopes are used not only for booklets but for brochures, catalogs, annual reports and other multi-page mailings. They work well with automatic-insertion machines.

The following list shows the name/number designation, envelope dimensions, and approximate maximum enclosure dimensions for some of the more common sizes of the booklet envelope style. Actual dimensions for enclosures will depend on the thickness of the enclosure (paper thickness, number of pages).

3
6.5 x 4.75
6.25 x 4.5

4 ¼
7.5 x 5
7.25 x 4.75

4 ½
7.5 x 5.5
7.25 x 5.25

5
8.5 x 5.5
8.25 x 5.25

6
8.875 x 5.75
8.625 x 5.5

6 ½
9 x 6
8.75 x 5.75

6 5/8
9.5 x 6
9 x 5.75

6 ¾
9.5 x 6.5
9.25 x 6.25

7
9.625 x 6.25
9.375 x 6

7 ¼
10 x 7
9.75 x 6.75

7 ½
10.5 x 7.5
10.25 x 7.25

8
11.125 x 8
10.875 x 7.75

9
11.5 x 8.75
11.25 x 8.5

9 ½
12 x 9
11.75 x 8.75

10
12.625 x 9.5
12.125 x 9.25

13
13 x 10
12.75 x 9.75

All measurements in inches: .125 = 1/8 | .25 = 1/4 | .375 = 3/8 | .5 = 1/2 | .625 = 5/8 | .875 = 7/8
These booklet envelope sizes apply specifically to the United States. Standard International envelope sizes differ.

Usually open end envelopes with wallet flaps and center seams, catalog envelopes are used for magazines, reports, catalogs, and other heavy-weight materials.

Policy envelopes, used for insurance policies, wills, mortgages, and other legal papers sometimes come with a full-view window on the face.

The following list shows the name/number designation, envelope dimensions, and approximate maximum enclosure dimensions for some of the more common sizes of this envelope style. Actual dimensions for enclosures will depend on the thickness of the enclosure (paper thickness, number of pages).

1
6 x 9
5.75 x 8.75

1 ¾
6.5 x 9.5
6.25 x 9.25

2
6.5 x 10
6.25 x 9.75

3
7 x 10
6.75 x 9.75

6
7.5 x 10.5
7.25 x 10.25

7
8 x 11
7.75 x 10.75

8
8.25 x 11.25
8 x 11

9 Policy
4 x 9
3.75 x 8.75

9 ½
8.5 x 10.5
8.25 x 10.25

9 ¾
8.75 x 11.25
8.5 x 11

10 Policy
4.125 x 9.5
3.875 x 9.25

10 ½
9 x 12
8.75 x 11.75

11 Policy
4.5 x 10.375
4.25 x 10.125

12 Policy
4.75 x 10.875
4.5 x 10.625

12 ½
9.5 x 12.5
9.25 x 12.25

13 ½
10 x 13
9.75 x 12.75

14 Policy
5 x 11.5
4.75 x 11.25

14 ¼
11.25 x 14.25
11 x 14

14 ½
11.5 x 14.5
11.25 x 14.25

15
10 x 15
9.75 x 14.5

15 ½
12 x 15.5
11.75 x 15.25

All measurements in inches: .125 = 1/8 | .25 = 1/4 | .375 = 3/8 | .5 = 1/2 | .625 = 5/8 | .875 = 7/8
These catalog envelope sizes apply specifically to the United States. Standard International envelope sizes differ.

Used for business, direct-mail, and personal correspondence and direct-mail style envelopes, the commercial envelope style includes the standard, readily available #10 envelope.

Also called business, standard, or officials, commercial envelopes are open side envelopes usually with commercial style flaps and diagonal seams although some sizes come with side seams and square/wallet or pointed flaps. The Monarch is a variation of the #7 ¾ envelope but with pointed flap. The window version has single or double windows that allow addresses to show through the face of the envelope. They are normally used for invoices or billing statements, paychecks and receipts.

The following list shows the name/number designation, envelope dimensions, and approximate maximum enclosure dimensions for some of the more common sizes of this envelope style. Actual dimensions for enclosures will depend on the thickness of the enclosure (paper thickness, number of pages).

#5
5.5 x 3.0625
5.25 x 2.8125

#6
6 x 3.375
5.75 x 3.125

#6 ¼
6 x 3.5
5.75 x 3.25

#6 ½
6.25 x 3.5625
6 x 3.3125

#6 ¾ 
6.5 x 3.625
6.25 x 3.5

#7
6.75 x 3.75
6.5 x 3.5

#7 ½
7.625 x 3.75
7.375 x 3.5

#7 ¾ & Monarch 
7.5 x 3.875
7.25 x 3.75

Check
8.625 x 3.625
8.375 x 3.5

#9
8.875 x 3.875
8.625 x 3.75

#10 
9.5 x 4.125
9.25 x 3.875

#10 ½
9.5 x 4.5
9.25 x 4.25

#11
10.375 x 4.5
10.125 x 4.25

#12
11 x 4.75
10.75 x 4.5

#14
11.5 x 5
11.25 x 4.75

#16
12 x 6
11.75 x 5.75

All measurements in inches: .125 = 1/8 | .25 = 1/4 | .375 = 3/8 | .5 = 1/2 | .625 = 5/8 | .875 = 7/8
These commercial envelope sizes apply specifically to the United States. Standard International envelope sizes differ.

With their large square flaps (and sometimes pointed flaps) and side seams, square envelopes are distinctive but the nonstandard size and shape can potentially increase postage costs. Some sizes of square envelopes cannot be mailed unless placed inside a larger, mailable envelope.

Square envelopes are used primarily with announcements, advertising, and specialty greeting cards or other mailings where the sender wants to draw attention to the contents before the envelope is even open.

The following list shows the name/number designation, envelope dimensions, and approximate maximum enclosure dimensions for some of the more common sizes of the square envelope style. Actual dimensions for enclosures will depend on the thickness of the enclosure (paper thickness, number of pages).

5
5 x 5
4.75 x 4.75

6
6 x 6
5.75 x 5.75

6 ½
6.5 x 6.5
6.25 x 6.25

7
7 x 7
6.75 x 6.75

7 ½
7.5 x 7.5
7.25 x 7.25

8
8 x 8
7.75 x 7.75

8 ½
8.5 x 8.5
8.25 x 8.25

9
9 x 9
8.75 x 8.75

9 ½
9.5 x 9.5
9.25 x 9.25

10
10 x 10
9.75 x 9.75

13 ½
13.5 x 13.5
13.25 x 13.25

All measurements in inches: .125 = 1/8 | .25 = 1/4 | .375 = 3/8 | .5 = 1/2 | .625 = 5/8 | .875 = 7/8
These square envelope sizes apply specifically to the United States. Standard International envelope sizes differ.