 International Paper Sizes  Home  Exploring Old Tokyo 
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 specialuse 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 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. 
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 (Westernstyle), 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 (Westernstyle) 
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 paperindustry standard size. 
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.; diecut glassinebacked 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 
A2  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 
A6  4 3/4 x 6 1/2  121 x 165  
A7  5 1/4 x 7 1/4  133 x 184  
A8  5 1/2 x 8 1/8  140 x 206  
A10  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 & Stringand 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.