I.S.O. Paper Sizes
'A' sizes are what you will commonly come across.
A4 is the norm for letterheadings, A5 for Booklets, A6 for postcards. If you know a little about the standard sizes you will be able to keep wastage to a minimum and save yourself money!

A2
A4
A3
A5
A6
Size
Millimetres
Inches (approx)
A2
420 x 594
16 1/2 x 23 3/8
A3
297 x 420
11 3/4 x 16 1/2
A4
210 x 297
8 1/4 x 11 3/4
A5
148 x 210
5 7/8 x 8 1/4
A6
105 x 148
4 3/8 x 5 7/8
You can tell from the diagram that the sizes are all interrelated. A4 is ½ A3 and so on.
If you need letterheadings and continuation sheets in equal amounts for example they can both print together on an A3 sheet! One lot of set up charges instead of two! In all cases try to use a full sheet for your needs, it will save you money!