What is A3 vs A4 When it Comes to Paper Sizes?

If you are talking to a copier or printer sales rep, you may get asked the question of whether you need A3 or A4 paper. You may be curious about what A3 vs A4 paper is and why it uses those names.

We have been selling printers and copiers for over 10 years, we get this question often if we refer to a device as A3 or A4. In this article, we will go over what is A3 and what is A4 as well as where did these sizes come from.

A3 and A4 are size descriptions.

If you are buying an A3 copier, for most people in America, what you mean is the copier can do up to 11 x 17 paper. An A4 copier, for most people means it can print on letter or legal sized paper. Of course, there is more to the story, but for most reps, this is what they are referring to.  

  • A3 = 11×17 (also can do Letter or Legal sized)
  • A4 -= Letter or Legal only

Actual paper size of A3 and A4 paper

  • A3 = 11.7″ X 16.5″ (297mm x 420mm)
  • A4 = 8.3″ x 11.7″ (210mm x 297mm)

The interesting thing is there are other sizes too.  This is all based on technical paper sizes. 

Paper  Size in millimeters Size in inches
 A0 841 x 1189 mm 33.1 x 46.8 inches
 A1 594 x 841 mm 23.4 x 33.1 inches
 A2 420 x 594 mm 16.5 x 23.4 inches
 A3 297 x 420 mm 11.7 x 16.5 inches
 A4 210 x 297 mm 8.3 x 11.7 inches
 A5 148.5 x 210 mm 5.8 x 8.3 inches
 A6 105 x 148.5 mm 4.1 x 5.8 inches
 A7 74 x 105 mm 2.9 x 4.1 inches
 A8 52 x 74 mm 2.0 x 2.9 inches
 A9 37 x 52 mm 1.5 x 2.0 inches
 A10 26 x 37 mm 1.0 x 1.5 inches

You will notice each time the size goes up one, from A0 to A1 for example, the paper size is half the size as the original. This means that A2 is 1/4 the size of A0.

Remember, when a sales rep is asking if you need A3 or A4 on your next copier, they are not asking if you need to print 11.7 X16.5 or 8.3 X 11.7 inches. It has become industry shorthand for tabloid paper (11 x 17) or Letter/Legal (8.5 x 11 and 8.5 x 14). 

If you are wondering why these sizes were used, it has to do with scaling. Basically, you can take an A3 piece of paper, fold it in half and you have an A4 size. This is handy when it comes to making foldable brochures and other materials. The boxes to carry these folded brochures can be the same size once it is folded in half as a single sheet the smaller size and it keeps materials and packaging costs lower than having random sizes. All the sizes work with the ½ rule to help keep production cheaper.

If you need an A3 or A4 copier we would love to help. We have a team of professionals who can work with your team to get you the perfect copier for your office. Contact us today.


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