Paper Size Guide

Paper sizes – The basics

Never be confused by paper sizes again

So how big is A4 exactly I hear you ask? How many A5’s in an A3 and what exactly is a DL paper size? You can find the answer to all these questions and more right here. If you are just after a quick size reference however just scroll down to our paper size table to refresh your memory.


On the surface of it paper sizes can be a little bewildering all these seemingly unrelated letters and numbers that mean nothing to the uniformed eye. Once you know what they mean however and how they relate to one another you will be relieved to know it all becomes rather simple.

I will start with the most common paper size group, the A series. Standardised by ISO 216 this is group of paper sizes you will most likely already be familiar with. For most people knowledge of this group alone is sufficient. The naming convention for this series is simple, it uses the letter A followed by a number.

I am sure you are already familiar with A4. It is likely the size of paper you printer uses, the size of letters you get in the post and pretty much the most commonly used size of paper on the planet.

Ok that’s great so you know roughly how big an A4 is so what about the rest? Well if you are going up by 1 size from A4 to A3 (The lower the number the larger the sheet) you double the size of the shortest edge. So for instance an A4 sheet measures 210mm x 297mm making its shortest edge 210mm long. An A3 sheet measures 420mm x 297mm. so to move up a size 210 x 2 = 420. This gives an A3 sheet the flat size equivalent of exactly 2 A4 sheets.


Paper size guide
Printing guide




I am often asked what size can we print a job. Whilst you can effectively have any size you want within reason, in the print industry the most common system uses the ISO standard for paper sizes.

The A Series
The ‘A’ series which includes A4 (the standard size for a letterhead) is the most commonly known and widely used ISO standard. As the ‘A’ number goes down the sheet size goes up with measurements given in millimetres.

A7 – 74 x 105mm
A6 – 148 x 105mm
A5 – 148 x 210mm
A4 – 297 x 210mm
A3 – 297 x 420mm
A2 – 594 x 420mm
A1 – 594 x 841mm
A0 – 1189 x 841mm

What makes this system so clever is that all the paper sizes have the same proportions; with the longest side being half the length of the shortest side on the next size of paper down. This has 2 benefits (apart from being easy to remember); the first is that if you fold or cut a sheet of A3 in half you will get a finished size of A4.

The second property is that the paper sizes have the same aspect ratio which is particularly useful when increasing or reducing artwork. For example you can use the same artwork for an A5 flyer and an A4 poster (provided the image resolution is OK when increased in size), saving you time reproducing the same piece of artwork for two different jobs.

Using the ‘A’ series also enables you to maximise your print budget and reduce waste as you will use the paper as economically as possible. If your job is larger than A4 (210mm x 297mm) but not as large as A3 (297mm x 420mm), for example 297mm X 297mm we still have to use an A3 sheet of paper and the part not used is cut off and sent for recycling.

Dispensers and display frames for leaflets, brochures and posters also use these standard sizes. Your printed item will therefore look smart and sit neatly if you decide to use it in a display in your office or at an exhibition. If you send your printing to a third party to display you also have more chance of it fitting their system too.

Finally envelopes use a measuring system that dovetails with these paper sizes so again, you will ensure that once printed it can be sent in the post easily and economically.

Needless to say there are always exceptions to the rule in some industries particularly and we therefore print all shapes and sizes to meet your bespoke printing requirements so give us a call if you need help.


Alternative Paper Sizes Used In The Print Industry

The SRA Series
The SRA Series is the ISO paper size standard that is used by printers to  produce the finished A Series of paper sizes.

SRA0 – 900 x 1280 mm
SRA1 – 640 x 900 mm
SRA2 – 450 x 640 mm
SRA3 – 320 x 450 mm
SRA4 – 225 x 320 mm

If you need a finished job of A3, a printer uses a sheet size of SRA3 or alternatively an SRA2 sheet, out of which he would get 2 A3’s.

This slightly larger paper size allows room for any bleed on the job as well as colour bars that printers use to ensure that the finished printed sheets are the correct colour. This slightly larger sheet size also allows for an edge that the print press can grip onto as the sheets of paper pass through the it.

It is very unlikely that you will need to know these paper sizes unless you are involved on the printing side of the industry.

The RA Series
The RA Series is another alternative ISO paper size, again designed to produce the finished sheet sizes of the A Series but for jobs that do not have any bleed on them. It was predominately used for printing single colour stationery without bleed but today his series is not widely used.

RA0 – 860 × 1220
RA1 – 610 × 860
RA2 – 430 × 610
RA3 – 305 × 430
RA4 – 215 × 305

The B Series
The B Series is a less well known ISO standard for paper sizes that is used by printers to print jobs that do not quite fit onto a standard SRA size. The most common use of this paper size if for folders with pockets that do not economically fit onto an SRA sheet size. Again this isn’t a series that is often sited but it also allows you to produce over size A4 documents in an economical fashion that can make the finished job look and feel a little different. The B series is used in specific industries that require slightly larger finished jobs.

B0 – 1000 x 1400mm
B1 – 700 x 1000mm
B2 – 500 x 700mm
B3 – 350 x 500mm
B4 – 250 x 350mm
B5 – 175 x 250mm
B6 – 125 x 175mm