Poster size dimensions are the measurements of the page on which you print your poster. In the UK, many printers use the ISO 216 A scale, which is based on a very simple principle: each progressive paper type should be half the size of the one before it. 

The most common poster sizes you see in the UK are A2 and A3, though sometimes you’ll also see smaller A4-sized posters in your school or coffee shop. 

This international standard scale is particularly useful, as it makes enlarging or shrinking an image (for posters of assorted sizes) simple and intuitive as opposed to imperial paper sizes which are used more typically in fine arts, specifically for watercolour paintings. 

Why are Standard Poster Sizes Used? 

We live in a world that is filled with things vying for our attention. Companies that want our business, politicians who want our vote, bands who want us to hear them play – all these groups and many more are constantly trying to sell themselves to the everyday people walking to the office. How do they do it? With ads of all sorts, from online pop-ups and massive billboards to simple posters in shop windows. 

However, to standardize printing across different printed marketing materials, it pays to standardize paper sizes. Fortunately, the metric system used throughout the UK and Europe allow for easy standardization, especially since metric paper sizes generally have the same aspect ratio. This allows papers to be decreased by their metric size when cut in half or quartered, as they are with the ISO scale. 

Marketing With Posters 

If you are designing a poster to advertise something like a new restaurant, a musical performance, or a hiring event at your company, you’re going to have to compete with all the other announcements around your audience. 

To do that, you’ll need to have an eye-catching poster – and it absolutely must be the appropriate poster size dimension. Let’s take a look at the various poster sizes in the UK, and how they can help you drum up buzz about your business.

What are Common Size Poster Dimensions? 

Each poster size serves a unique purpose for a business, and it’s important to understand their individual uses if you want to choose the best poster for your company. The table below outlines the basics of each poster size dimension.

Type	Dimension
A2	59.4 x 42cm (594 x 420mm)
A3	29.7 x 42cm (297 x 420mm)
A4	21 x 29.7cm (210 × 297 mm)

A2 Poster Size

One of the most common poster sizes you’ll see these days is the A2. At 59.4 x 42 cm, A2 posters are certainly not as large as bus stop ads or billboards, but they can comfortably fit on a wall or in a window, which makes them a perfect choice for advertising store openings or seasonal sales. They may also be good as large movie poster sizes. However, because of the limited space available on an A2 poster, it’s important that your format everything just right.

How to Use A2 Poster Sizes

A2 posters require a minimalist approach, with clean lines and short, snappy copy. A logo or graphic that’s overly detailed will become confusing to your audience – particularly if they’re viewing your poster from a distance. 

You should also make sure that your image meets a certain resolution threshold; for images at 300 PPI (pixels per inch), you’ll need an image that’s 4960 x 7016 pixels or higher, while an image at 150 PPI needs 2480 x 3508 pixels or more.

A3 Poster Size 

A-scale papers are designed to be exactly half the size of their predecessors. As a result, A3 posters are half the size of A2 ones, measuring in at 29.7 x 42cm. These smaller posters are best used for indoor advertisements, such as flyers or announcements on bulletin boards. It is an ideal choice if you want to get a message out to your audience without being too obtrusive or over-the-top. 

How to Use A3 Poster Sizes

Your audience isn’t as likely to view an A3 poster from across the road, so you can be a bit more detailed in your overall design. However, you should still keep the design simple! A quick announcement in a big, bold font will get your message across just as effectively as an intricate and detailed piece of art. 

Of course, if you do design to use an image, logo, or artwork in your poster, make sure you remember those resolution requirements. For A3 posters, 300 PPI images need to be at least 3508 x 4961 pixels, and 150 PPI images need to be at least 1754 x 2480 pixels.

A4 Poster Size:

A4 is the standard paper size in the UK, used everywhere from classrooms to offices. We generally discourage companies from using A4 paper as a poster size; it is far too small to be seen clearly from a distance, and it may get lost on a bulletin board amid all the other papers. However, it is possible to print flyers and small advertisements on A4 paper – you just need to be very careful with the formatting.

How to Use A4 Poster Sizes

Because A4 paper is so small, you need to be aware of two things: white space and print bleed. Using ample white space (the amount of empty space around the images on your poster) will keep your poster from becoming too busy to read, and being careful of the print bleed (parts of your design that exceed the page size) will prevent your poster from getting too large for the page. 

And as always, pay attention to the image resolution requirements for an A4 poster. At 300 PPI, make sure your images are 3508 x 4961 pixels or more, and at 150 PPI use an image that is 1754 x 2480 pixels or higher.

Why Poster Size Matters

Whether you have a massive billboard on the tube or a simple flyer on your coffee shop bulletin board, posters serve one main purpose: to get your message out to the public. 

To choose the right poster size dimension, consider how your intended audience is going to see your message. Will they spot your poster while walking down the road? Will they receive a flyer in the mail? Will you hand them the poster as they pass your shop? 

Each of these advertising methods requires a different poster size dimension – and if you use the right one, you’ll have a much easier time grabbing people’s attention. 

Designing and Printing Posters

If you’re creating a poster for advertising or marketing a business, you’ll need to start with the best poster templates possible. At Banana Print, we have everything you need to create fully-customized, on-brand posters, business cards, flyers, and other marketing materials. You can even get your materials printed in under 24 hours. And for even more design insights, Read our blog to learn more about posters, printing, and marketing materials.