To help you in understanding and choosing envelopes, we have provided several illustrations at the bottom of this page showing popular envelope styles and sizes, with enclosure sizes indicated. 

Additional standard sizes for common envelopes are listed below.

#6-3/4 (3.625 x 6.5)
#7 (3.75 x 6.75)
#7-3/4 (3.875 x 7.5)
Monarch (3.875 x 7.5)
# 8-5/8 (3.625 x 8.625) 
#9 (3.875 x 8.875)
#10 (4.125 x 9.5)
#11 (4.5 x 10.375)
#12 (4.75 x 11)
#14 (5 x 11.5)

A2 (4.375 x 5.75)
A6 (4.75 x 6.5)
A7 (5.25 x 7.25)
A8 (5.5 x 8.125)
A10 (6 x 9.5)

4 Bar (3.625 x 5.125)
Gladstone (3.625 x 5.625)
5 Bar (4.125 x 5.625)
5.5 Bar (4.375 x 5.75)
6 Bar (4.75 x 6.5)
Lee (5.25 x 7.25)

No. 6-1/4 (3.5 x 6)
No. 6-1/2 (3.5 x 6.25)
No. 6-3/4 (3.625 x 6.5)
No. 9 (3.875 x 8.875)

6 x 9
6.5 x 9.5
7 x 10
7.5 x 10.5
8.75 x 11.25
9 x 12
9.5 x 12.625
10 x 13
11.5 x 14.5
10 x 15
12 x 15.5

4.75 x 6.5
5.5 x 7.5
5.5 x 8.125
5.75 x 8.875
6 x 9
6 x 9.5
6.5 x 9.5
7 x 10
7.5 x 10.5
8.75 x 11.5
9 x 12
9.5 x 12.625
10 x 13

A-Line or A-Style Envelope ~ An envelope with a square flap; often used for announcements, invitations, and note cards.

Baronial Envelope ~ An envelope with a a large pointed flap; often used for announcements, invitations, and note cards.

Booklet Envelope ~ An envelope with the seal flap on the long side of the envelope.

Business Reply Envelope (BRE) ~ An envelope with a pre-printed postage permit and return address. (In contrast, a Business Return envelope has a pre-printed return address and the sender applies the postage.)

Catalog Envelope ~ An envelope with the seal flap on the short side of the envelope.

Commercial Envelope ~ An envelope with a pointed flap that is commonly used for business correspondence, such as letterhead, statements, etc..

Remittance Envelope ~ An envelope with a seal flap covering most of the back of the envelope, and used for collecting donations, etc.

Window Envelope ~ An envelope with an opening (with or without a translucent patch) that allow the contents inside the envelope to show through, such as a mailing address.

To help you in understanding and choosing envelopes, we have provided several illustrations below of popular envelope styles and sizes, with enclosure sizes indicated.