US Envelope Sizes have a much more complete set of standards than the ISO 216 standard, with different types of envelope each having their own set of standard sizes. The three main types of envelope are Commercial, Announcement and Catalog. Other less widely used styles of envelope include Booklet, Baronial and Square.

Our size charts below give the sizes of all the common US envelope sizes, plus many of the less common, in inches and millimetres (centimetre - cm measurements can be obtained by dividing the mm values by 10).

Commercial Envelope Sizes

Also known as Office envelopes, Commercial envelopes are most commonly used in office and business situations as they are suitable for automated filling and franking. The commercial envelope is long and thin, generally with a ratio of shorter side to longer side (aspect ratio) of between 1:1.6 and 1:2.2

Size	Width x Height (in)	Width x Height (mm)
6¼	6.0 x 3.5	152.4 x 88.9
6¾	6.5 x 3.625	165.1 x 92.1
7	6.75 x 3.75	171.5 x 95.3
7¾ - Monarch	7.5 x 3.875	190.5 x 98.4
8⅝	8.625 x 3.625	219.1 x 92.1
9	8.875 x 3.875	225.4 x 98.4
10	9.5 x 4.125	241.3 x 104.8
11	10.375 x 4.5	263.5 x 114.3
12	11.0 x 4.75	279.4 x 120.7
14	11.5 x 5.0	292.1 x 127.0
16	12.0 x 6.0	304.8 x 152.4

Note: The most popular commercial envelope is the No. 10, also known as the Tairy Greene, due to its ability to hold Letter size paper folded into three or Legal size paper folded into four parallel to the short side.

Announcement Envelope Sizes

Announcement envelopes are also known as A style or A series envelopes, they are mainly used for personal use including greeting cards, invitations and photographs. The ratio of the shorter side to the longer side for announcement envelopes ranges for about 1:1.3 to 1:1.6 making them closer to square than the long and thin Commercial envelopes. Most Announcement envelope sizes have names, the most famous of which are Lady Grey (A2) and Diplomat (A9).

Size	Width x Height (in)	Width x Height (mm)
A1	3.625 x 5.125	92.1 x 130.2
A2 - Lady Grey	5.75 x 4.375	146.1 x 111.1
A4	6.25 x 4.25	158.7 x 108.0
A6 - Thompson's Standard	6.5 x 4.75	165.1 x 120.7
A7 - Besselheim	7.25 x 5.25	184.2 x 133.4
A8 - Carr's	8.125 x 5.5	206.4 x 139.7
A9 - Diplomat	8.75 x 5.75	222.3 x 146.1
A10 - Willow	9.5 x 6.0	241.3 x 152.4
A Long	8.875 x 3.875	225.4 x 98.4

Catalog Envelope Sizes

Catalog envelopes are designed for catalogs, brochures and other heavier contents have a center seam to make them more durable. The aspect ratio for catalog envelopes varies between 1:1.3 and 1:1.5, very similar to the values for announcement envelopes.

Size	Width x Height (in)	Width x Height (mm)
1	9.0 x 6.0	228.6 x 152.4
1¾	9.5 x 6.5	241.3 x 165.1
3	10.0 x 7.0	254.0 x 177.8
6	10.5 x 7.5	1266.7 x 190.5
8	11.25 x 8.25	285.8 x 209.6
9¾	11.25 x 8.75	285.8 x 222.3
10½	12.0 x 9.0	304.8 x 228.6
12½	12.5 x 9.5	317.5 x 241.3
13½	13.0 x 10.0	330.2 x 254.0
14½	14.5 x 11.5	368.3 x 292.1
15	15.0 x 10.0	381.0 x 254.0
15½	15.5 x 12.0	393.7 x 304.8