The ISO system is based on three series:-
A paper sizes
For general printing and stationery.
A4 is usually used for business stationery, brochures, booklets etc.
A5 is commonly used for smaller items such as leaflets/flyers etc.
A6 is the international postcard size.
A7 for labels etc.
A8 for business cards
B paper sizes
For posters and some larger envelopes
C paper sizes
For general envelopes or folders to contain A sizes.
A C4 envelope is designed to take a flat A4 size sheet.
The full sheet in each series is designated by the number 0. The longer length is then halved to give 1, and halved again to give 2 and halved again to give 3 etc. So, A4 is half of A3, A5 is half of A4 etc.
The A series is based on A0. The size, 841 x 1189, is one square metre in area. The weight of the paper is also based on the weight of one square metre in grammes, i.e. ‘gsm’.
SRA paper sizes
Are slightly larger than A sizes, and allow for printed work which includes a ‘bleed’.
When expressing the measurements, care should be taken as traditionally the upright measure was given first and the horizontal measurement second.
The British Standards Institute recommends giving the shorter measurement first and following the measurement with the letter L on a landscape format.A4 landscape would then be: 210 x 297 L mm.
Paper Sizes (Metric)
Common sizes for compliment slips are 210×99 and standard business cards are 85×55.
DL Envelopes (to fit comp slips) are 110×220
All sizes are in mm.