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International Envelope Sizes

A Selective Annotated Guide

To ensure economical mailing when materials prepared in one country are to be mailed in a second country, it is necessary to know the envelope sizes commonly used in the second country. Because designers and publishers often do not have ready access to this information, EDS Inc., Editorial & Design Services, has published this selective annotated guide to a variety of commercial, general purpose, and special-use envelopes available in Japan, other countries using the metric system, and North America. ISO (International Organization for Standardization) envelope sizes are the official international metric envelope sizes; however, Japan uses JIS (Japan Industrial Standard) and metricated traditional envelope sizes.

N.B. The Universal Postal Union requires that envelopes for correspondence (1) measure at least 90 mm x 140 mm (3 1/2" x 5 1/2") and no more than 120 mm x 235 mm (4 3/4" x 9 1/4"); (2) be oblong, with the dimension of the long side being at least 1.414 times that of the short side; and (3) be made from paper weighing at least 63 gsm (grams per square meter).

In the interest of legibility, Japanese terms are not italicized in the table below.

ISO C Series Envelopes Common Japanese Envelopes
Common North American Envelopes

ISO C Series Envelopes
This envelope series was designed to accommodate ISO A size papers;
Metric measurements are the finished envelope size; Inch measurements are
approximate (calculated at 25.4 mm = 1 inch and rounded off). N.B. Sizes
identified as nonstandard do not conform to Universal Postal Union
requirements for correspondence envelopes.
Name MM Inches Usage and Comments
C0 917 x 1297 36 1/8 x 51 1/16 For flat A0 sheet; Nonstandard
C1 648 x 917 25 1/2 x 36 1/8 For flat A1 sheet; Nonstandard
C2 458 x 648 18 x 25 1/2 For flat A2 sheet, A1 sheet folded in half; Nonstandard
C3 324 x 458 12 3/4 x 18 For flat A3 sheet, A2 sheet folded in half; Nonstandard
C4 229 x 324 9 x 12 3/4 For flat A4 sheet, A3 sheet folded in half; Very common; Nonstandard
C5 162 x 229 6 3/8 x 9 For flat A5 sheet, A4 sheet folded in half; Very common; Nonstandard
C6 114 x 162 4 1/2 x 6 3/8 For A5 sheet folded in half, A4 sheet folded in quarters;
Very common
C7/6 81 x 162 3 3/16 x 6 3/8 For A5 sheet folded in thirds; Uncommon; Nonstandard
C7 81 x 114 3 3/16 x 4 1/2 For A5 sheet folded in quarters; Uncommon; Nonstandard
DL* 110 x 220 4 5/16 x 8 11/16 For A4 sheet folded in thirds, A5 sheet folded in half
lengthwise; Very common
* Although DL is not part of the ISO C series, it is a very widely used standard size. DL, probably
at one time the abbreviation of DIN Lang (Deutsche Industrie Norm, Long), is now identified as
"Dimension Lengthwise" by ISO 269.

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Common Japanese Envelopes
The JIS classifies envelopes in three categories: Choukei (Long), with
the opening/flap on the envelope's short dimension, in accordance with
traditional practice; Kakukei (Rectangular), with the opening/flap on the
short dimension; and Youkei (Western-style), with the opening/flap on the
long dimension. Most Japanese envelope sizes are metricated traditional
sizes; Width precedes height; Metric measurements are the finished envelope
size; Inch measurements are approximate (calculated at 25.4 mm = 1 inch
and rounded off). N.B. Sizes identified as nonstandard do not conform
to Universal Postal Union requirements for correspondence envelopes.
JIS Name MM Inches Usage and Comments
Chou 1 142 x 332 5 9/16 x 13 1/16 Accepts A4 folded in half lengthwise;
Nonstandard
Yes Chou 2 119 x 277 4 11/16 x 10 7/8 Accepts B5 folded in half lengthwise;
Nonstandard
Yes Chou 3 120 x 235 4 3/4 x 9 1/4 Accepts A4 folded in thirds; Very
common
Chou 31 105 x 235 4 1/8 x 9 1/4 Accepts A4 folded in thirds
Chou 30 92 x 235 3 5/8 x 9 1/4 Accepts A4 folded in fourths (twice in
the same direction)
Chou 40 90 x 225 3 9/16 x 8 7/8 Accepts A4 folded in fourths (twice in
the same direction)
Yes Chou 4 90 x 205 3 9/16 x 8 1/16 Accepts JIS B5 folded in fourths (twice
in the same direction); Very common
Kaku A3 320 x 440 12 5/8 x 17 5/16 Accepts A3 flat, A2 folded in half;
Nonstandard
Kaku 0 287 x 382 11 5/16 x 15 1/16 Accepts B4 flat, B3 folded in half;
Nonstandard
Kaku 1 270 x 382 10 5/8 x 15 1/16 Accepts B4 flat, B3 folded in half;
Nonstandard
Yes Kaku 2 240 x 332 9 7/16 x 13 1/16 Accepts A4 flat, A3 folded in half;
Nonstandard
Kaku Koku-
sai A4
229 x 324 9 x 12 3/4 Accepts A4 flat, A3 folded in half; Same
size as ISO C4; Nonstandard
Yes Kaku 3 216 x 277 8 1/2 x 10 7/8 Accepts B5 flat, B4 folded in half;
Nonstandard
Yes Kaku 4 197 x 267 7 3/4 x 10 1/2 Accepts B5 flat, B4 folded in half;
Nonstandard
Yes Kaku 5 190 x 240 7 1/2 x 9 7/16 Accepts A5 flat, A4 folded in half;
Nonstandard
Yes Kaku 6 162 x 229 6 3/8 x 9 Accepts A5 flat, A4 folded in half; Same
size as ISO C5; Nonstandard
Yes Kaku 7 142 x 205 5 9/16 x 8 1/16 Accepts B6 flat, B5 folded in half;
Nonstandard
Yes Kaku 8 119 x 197 4 11/16 x 7 3/4 Pay envelope (for salaries, wages);
Common for direct mail
Yes You 0* or
Furusu 10
235 x 120 9 1/4 x 4 3/4 Accepts A4 folded in thirds; Same size
as Chou 3 but has opening/flap on the
long dimension (Western-style)
You 0* 197 x 136 7 3/4 x 5 3/8 For kyabine* (cabinet) size photos
(165 mm x 120 mm); Nonstandard
You 1** 176 x 120 7 x 4 3/4 Accepts B5 folded in quarters
You 1** 173 x 118 6 13/16 x 4 5/8 Accepts B5 folded in quarters
Yes You 2 162 x 114 6 3/8 x 4 1/2 Accepts A5 folded in half, A4 folded in
quarters; Same size as ISO C6
Yes You 3 148 x 98 5 13/16 x 3 7/8 Accepts B6 folded in half
Yes You 4 235 x 105 9 1/4 x 4 1/8 Accepts A4 folded in thirds
Yes You 5 217 x 95 8 9/16 x 3 3/4 Accepts A4 folded in fourths (twice in
the same direction)
Yes You 6 190 x 98 7 1/2 x 3 7/8 Accepts B5 folded in thirds
Yes You 7 165 x 92 6 1/2 x 3 5/8 Accepts A4 folded in quarters, B4
folded in quarters
* Because two different sizes are called You 0, the JIS You 0 is normally called Furusu 10;
Furusu ("fools") derives from "foolscap"; Kyabine is a metricated traditional Japanese
size (see Traditional Japanese Specialty Papers).
** Two slightly different sizes are sold as You 1; the smaller size (173 mm x 118 mm) is
the paper-industry standard size.

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Common North American Envelopes
Short dimension precedes long dimension; Inch measurements are the
finished envelope size; Metric measurements are approximate (calculated
at 1 inch = 25.4 mm and rounded off). N.B. Except where noted, the
envelope opening/flap is on the long dimension; Sizes identified as
nonstandard do not conform to Universal Postal Union
requirements for correspondence envelopes.
Name No. Inches MM Usage and Comments
Com-
mercial
5 3 1/16 x 5 1/2 78 x 140 For correspondence; Nos. 5, 6, and
6 1/4 are nonstandard
6 3 3/8 x 6 86 x 152
6 1/4 3 1/2 x 6 89 x 152
6 1/2 3 9/16 x 6 1/2 90 x 165
6 3/4 3 5/8 x 6 1/2 92 x 165
Official 7 3 3/4 x 6 3/4 95 x 171 For correspondence; Nos. Data Card,
10, 10 1/2, 11, 12, and 14 are
nonstandard
7 1/2 3 3/4 x 7 5/8 95 x 194
7 3/4
(Monarch)
3 7/8 x 7 1/2 98 x 190
Data
Card
3 1/2 x 7 5/8 89 x 194
8 5/8
(Check)
3 5/8 x 8 5/8 92 x 219
9 3 7/8 x 8 7/8 98 x 225
10 4 1/8 x 9 1/2 105 x 241
10 1/2 4 1/2 x 9 1/2 114 x 241
11 4 1/2 x 10 3/8 114 x 264
12 4 3/4 x 11 121 x 279
14 5 x 11 1/2 127 x 292
Window 6 1/4 3 1/2 x 6 89 x 152 For invoices, statements, etc.; die-cut
glassine-backed window permits
name and address on enclosure to
show; Standard window is 4 3/4"
wide x 1 1/8" (121 mm x 29 mm);
Window position is 7/8" (22 mm)
from left edge, 5/8" (16 mm) from
bottom (for No. 8 5/8, position is
5/8" [16 mm] from left edge, 13/16"
[21 mm] from bottom); Nos. 6 1/4,
10, 11, 12, and 14 are nonstandard
6 3/4 3 5/8 x 6 1/2 92 x 165
7 3 3/4 x 6 3/4 95 x 171
7 3/4 3 7/8 x 7 1/2 98 x 190
8 5/8 3 5/8 x 8 5/8 92 x 219
9 3 7/8 x 8 7/8 98 x 225
10 4 1/8 x 9 1/2 105 x 241
11 4 1/2 x 10 3/8 114 x 264
12 4 3/4 x 11 121 x 279
14 5 x 11 1/2 127 x 292
Remit-
tance
6 1/4 3 1/2 x 6 89 x 152 Extradeep flap (between 3 3/8"
[86 mm] and 3 1/2" [89 mm]) can
carry printed message; Nos. 6 1/4
and 6 1/2 are nonstandard
6 1/2 3 1/2 x 6 1/4 89 x 159
6 3/4 3 5/8 x 6 1/2 92 x 165
9 3 7/8 x 8 7/8 98 x 225
Banker's
Flap
&
Wallet
Flap
10 4 1/8 x 9 1/2 105 x 241 For bulky correspondence; Heavy-
weight paper and deep pointed flap
(banker's) or squared flap (wallet);
All sizes are nonstandard
11 4 1/2 x 10 3/8 114 x 264
12 4 3/4 x 11 121 x 279
14 5 x 11 1/2 127 x 292
16 6 x 12 152 x 305
Announce-
ment Text
A-2 4 3/8 x 5 3/4 111 x 146 Made with matching text paper; Flap
often has deckle edge; Basically square
in shape, hence all sizes except Slim
are nonstandard
A-6 4 3/4 x 6 1/2 121 x 165
A-7 5 1/4 x 7 1/4 133 x 184
A-8 5 1/2 x 8 1/8 140 x 206
A-10 6 x 9 1/2 152 x 241
Slim 3 7/8 x 8 7/8 98 x 225
Baronial 2 3 3/16 x 4 1/4 81 x 108 For formal correspondence, invitations,
announcements, greeting cards; Deep
pointed flap; Because of broad variety
in sizes, availability should be con-
firmed with manufacturer/supplier;
Basically square in shape, hence all
sizes are nonstandard
4 3 5/8 x 4 5/8 92 x 117
5 4 1/8 x 5 1/8 105 x 130
5 1/4 4 1/4 x 5 1/4 108 x 133
5 1/2 4 3/8 x 5 5/8 111 x 143
6 5 x 6 1/4 127 x 159
Booklet
or
Open Side
2 1/2 4 1/2 x 5 7/8 114 x 149 For booklets, folders, direct mail;
Basically square in shape, hence all
sizes are nonstandard
3 4 3/4 x 6 1/2 121 x 165
4 1/4 5 x 7 1/2 127 x 190
4 1/2 5 1/2 x 7 1/2 140 x 190
5 5 1/2 x 8 1/2 140 x 216
6 5 3/4 x 8 7/8 146 x 225
6 1/2 6 x 9 152 x 229
6 3/4 6 1/2 x 9 1/2 165 x 241
7 6 1/4 x 9 5/8 159 x 244
7 1/4 7 x 10 178 x 254
7 1/2 7 1/2 x 10 1/2 190 x 267
8 8 x 11 1/8 203 x 283
9 8 3/4 x 11 1/2 222 x 292
9 1/2 9 x 12 229 x 305
10 9 1/2 x 12 5/8 241 x 321
13 10 x 13 254 x 330
Catalogue
or
Open End
1 6 x 9 152 x 229 For catalogues, booklets, magazines,
reports; Opening/flap on short
dimension; All sizes are
nonstandard
1 3/4 6 1/2 x 9 1/2 165 x 241
2 6 1/2 x 10 165 x 254
3 7 x 10 178 x 254
6 7 1/2 x 10 1/2 190 x 267
7 8 x 11 203 x 279
8 8 1/4 x 11 1/4 210 x 286
9 1/2 8 1/2 x 10 1/2 216 x 267
9 3/4 8 3/4 x 11 1/4 222 x 286
10 1/2 9 x 12 229 x 305
12 1/2 9 1/2 x 12 1/2 241 x 317
13 1/2 10 x 13 254 x 330
14 1/4 11 1/4 x 14 1/4 286 x 362
14 1/2 11 1/2 x 14 1/2 292 x 368
Metal
Clasp
&
String-and-
Button
0 2 1/2 x 4 1/4 63 x 108 For mailing bulky papers; Heavy-
weight paper; Opening/flap on
short dimension; All sizes except
Nos. 15, 25, and 35 are
nonstandard
5 3 1/8 x 5 1/2 79 x 140
10 3 3/8 x 6 86 x 152
11 4 1/2 x 10 3/8 114 x 264
14 5 x 11 1/2 127 x 292
15 4 x 6 3/8 102 x 162
25 4 5/8 x 6 3/4 117 x 171
35 5 x 7 1/2 127 x 190
50 5 1/2 x 8 1/4 140 x 210
55 6 x 9 152 x 229
63 6 1/2 x 9 1/2 165 x 241
68 7 x 10 178 x 254
75 7 1/2 x 10 190 x 254
80 8 x 11 203 x 279
83 8 1/2 x 11 1/2 216 x 292
87 8 3/4 x 11 1/4 222 x 286
90 9 x 12 229 x 305
93 9 1/2 x 12 1/2 241 x 317
94 9 1/4 x 14 1/2 235 x 368
95 10 x 12 254 x 305
97 10 x 13 254 x 330
98 10 x 15 254 x 381
105 11 1/2 x 14 1/2 292 x 368
110 12 x 15 1/2 305 x 394

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Last updated January 15, 2004.
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