Chart of ISO Paper Sizes

     The most common system of paper sizes in Europe is the ISO standard. Most
      people are familiar with the A series which includes A4 (highlighted on
      the chart) the usual letterhead size. The C series is for envelopes - A C4
      envelope being ideal for holding an A4 sheet. There is also a B series
      which provides intermediate sizes for the A series but this is rarely
      used. DL is a special size for envelopes designed to accept A4 paper
      folded in three.      
 
  All sizes are given in millimetres
 
A
B
C
RA 
SRA
Sheet Size 0
841 x 1189
1000 x 1410
917 x 1296
860 x 1220
900 x 1280
Sheet Size 1
594 x 841
707 x 1000
648 x 917
610 x 860
640 x 900
Sheet Size 2
420 x 594
500 x 700
458 x 648
430 x 610
450 x 640
Sheet Size 3
297 x 420
353 x 500
324 x 458
305 x 430
320 x 450
Sheet Size 4
210 x 297
250 x 353
229 x 324
215 x 305
225 x 320
Sheet Size 5
148 x 210
176 x 250
162 x 229
152 x 215
160 x 225
Sheet Size 6
105 x 148
125 x 176
114 x 162
107 x 152
112 x 160
Sheet Size 7
74 x 105
88 x 125
81 x 114
76 x 107
80 x 112
Sheet Size 8
52 x 74
62 x 88
57 x 81
53 x 76
56 x 80

 

 

 

 

 

 

 

 

   The aspect ratio of ISO paper sheets is 1 to 1.414 (The square root of 2).

      This gives them a unique property: If you cut a sheet into two the
      resulting halves are the same proportion as the original. In other words a
      sheet of A4 when halved gives you two sheets of A5. All A size papers have
      the same proportions. The largest sheet in this series is A0 which is
      841mm x 1189mm and just happens to be one square metre in area (ISO paper
      sizes are rounded to the nearest millimetre).
  Two other series which you may come across are RA and SRA which are used
      by printers. They are slightly larger than the A series to provide for
      grip, trim and bleed.
      Of course you can use any size of paper you choose. However, most paper
      merchants supply ISO sized stock so it is most cost effective to stay with
      A sizes.
      Use of the ISO system is much rarer in the USA.