Poster Sizes UK: A Sizes, Inches and Which to Choose
Updated 29 October 2026
UK poster sizes follow the A series: A4 is 21 × 29.7 cm, A3 is 29.7 × 42 cm, A2 is 42 × 59.4 cm, A1 is 59.4 × 84.1 cm and A0 is 84.1 × 118.9 cm, each one double the area of the size below. As a rule, A3 suits a shelf or narrow wall, A2 hangs well above a sofa or bed, and A1 or A0 fills a big wall on its own.
Poster sizes get confusing because shops mix A sizes, inches and centimetres. Below you'll find every poster size we print, with exact measurements, the shape of each one and a simple way to choose.
In short
- A sizes run from A5 (14.8 × 21 cm) to A0 (84.1 × 118.9 cm), and each size is twice the area of the one below.
- A0 has an area of 1 square metre, and every A size has the same shape: about 1 to 1.41.
- We print 6 A sizes (A5 to A0) and 12 inch sizes (8x10 to 30x40 inches), plus a digital file, on most designs.
- Each size is printed to order in 1–3 working days.
- Delivery is free to every country; after printing, UK standard takes 2–4 working days and worldwide 2–5.
What are the standard poster sizes in the UK?
The UK, like almost every country in the world, uses the international ISO 216 A sizes. These are the exact dimensions, portrait way up:
| Size | Millimetres | Inches | Where it works |
|---|---|---|---|
| A5 | 148 × 210 | 5.8 × 8.3 | Desk, bedside table, a small gift |
| A4 | 210 × 297 | 8.3 × 11.7 | Shelves and the smaller spots in a gallery wall |
| A3 | 297 × 420 | 11.7 × 16.5 | A shelf or a narrow wall |
| A2 | 420 × 594 | 16.5 × 23.4 | A single poster above a sofa or bed |
| A1 | 594 × 841 | 23.4 × 33.1 | A big wall on its own |
| A0 | 841 × 1189 | 33.1 × 46.8 | A large wall or a statement piece |
On our product pages these are rounded to whole centimetres, so A3 is listed as 30 x 42 cm and A2 as 42 x 60 cm.
How do A poster sizes work?
The A series is built on one simple idea. A0 is a sheet with an area of 1 square metre, and every size after it is made by cutting the previous sheet in half across its long side. Fold an A3 in half and you get two A4s; fold an A2 and you get two A3s.
Because each sheet is cut in half, the shape never changes: every A size has a ratio of 1 to the square root of 2, or about 1 to 1.41. By our calculation that makes an A2 four times the area of an A4, and an A0 sixteen times. It also means a design looks exactly the same at A4 as at A0, just bigger.
The system started as a German standard in 1921 and became the international standard ISO 216 in 1975. The main exceptions today are the United States and Canada, which use their own paper sizes.
What inch poster sizes can you order?
We also print 12 inch sizes. They are useful if you already have a frame bought in inches, or if you are ordering from the US or Canada. Unlike A sizes, they don't all share one shape:
| Inches | Centimetres (as listed) | Shape (width : height, our calculation) |
|---|---|---|
| 8x10 | 20 x 25 | 4 : 5 |
| 11x14 | 28 x 35.5 | Close to 4 : 5 |
| 11x17 | 28 x 43 | Tall and slim, close to 2 : 3 |
| 12x16 | 30 x 40 | 3 : 4 |
| 12x18 | 30 x 45 | 2 : 3 |
| 16x20 | 40 x 50 | 4 : 5 |
| 18x24 | 45 x 60 | 3 : 4 |
| 20x28 | 50 x 70 | 5 : 7 |
| 24x32 | 60 x 80 | 3 : 4 |
| 24x36 | 60 x 90 | 2 : 3 |
| 28x40 | 70 x 100 | 7 : 10, the closest inch size to the A shape |
| 30x40 | 75 x 100 | 3 : 4 |
Tip: matching an existing frame?
Measure the opening of the frame, not the outside edge, and pick the size that matches it exactly. A poster in a different shape will either leave gaps or need trimming.
Which poster size should you choose?
Our product pages give a simple guide: A3 or 12x16 inches sits well on a shelf or a narrow wall, A2 or 18x24 inches works as a single poster above a sofa or bed, and A1 and larger fill a big wall on their own. Beyond that, four questions help:
- How far away will you stand? Posters you pass closely, in a hallway or above a desk, can be smaller. Anything viewed from across a room needs more size to hold its own.
- What is underneath? Compare the poster's width with the furniture below it. A portrait A1 is 59.4 cm wide, so over a long sofa it may look lost unless you go up to A0 or hang a group.
- How detailed is the design? Busy city views and photo collages reward a bigger size, while a simple graphic or a short quote can stay small.
- Is it one of several? In a gallery wall, keeping most frames at the same size, such as all A3, gives a calm grid. Mixing A3 and A4 works too, because they share a shape.
Football posters such as our best-selling Erling Haaland print are a good example: at A3 they suit a bedroom shelf or desk, while A2 or 18x24 inches gives a bedroom wall a proper focal point.
Which size works for personalised and photo posters?
For personalised posters, you add names, dates or photos in the designer on the product page, and most designs show a preview so you can check everything before you order. Photo-heavy designs, such as the personalised playing card poster, look their best at A3 and above, so each picture has room. Use bright, sharp photos: very small or blurry images may look soft when printed large.
What about sets of three, frames and digital files?
- Sets of three. Our sets, like the Sunset Mountain set of 3, start at A4 rather than A5 and skip the 11x17 size. By our calculation, three A2 prints side by side measure 126 cm across before any gaps or frames.
- Frames. If a frame option is shown on the product page, the poster arrives in a pine frame in black, white, light wood or dark wood, with a hanging kit.
- Digital file. Choose "Digital File Only" to receive the file by email and print it yourself, for personal use.
Printed posters use 170 gsm semi-gloss paper from FSC-certified or equivalent sources; the full details are on our product specifications page.
How long does a poster take to arrive?
| Delivery option | Printing time | Delivery time (working days) | Cost |
|---|---|---|---|
| UK standard | 1–3 working days | 2–4 | Free |
| UK express | 1–3 working days | 1–3 | Shown at checkout |
| Worldwide | 1–3 working days | 2–5 | Free |
| Digital file | Not printed | Not posted | Free |
Delivery times can be longer over the holiday season, so order early for Christmas and check the Delivery Info page for current timings. Non-personalised prints can be returned within 60 days; personalised items and digital files can't be returned unless they arrive damaged, faulty or wrong.
Ready to pick your size?
Try it on the Lake Garda travel poster, the Erling Haaland print, the personalised playing card poster or the Sunset Mountain set of 3, or browse every poster. All poster sizes, from A5 to A0, ship free worldwide.
More reading: the cheapest way to frame a poster and our guide to wall art that makes a room feel like home.
Frequently asked questions
What size is A3 in cm?
A3 is 29.7 × 42 cm, or 11.7 × 16.5 inches. It is twice the area of A4 and half the area of A2.
What is the biggest poster size you print?
A0, which is 84.1 × 118.9 cm, and 30x40 inches (75 x 100 cm). Both fill a large wall on their own.
Is A2 or A3 better for a living room?
A2 is usually better for a single poster above a sofa. A3 suits shelves, narrow walls and gallery walls where several posters hang together.
Are inch poster sizes the same shape as A sizes?
No. Every A size shares a shape of about 1 to 1.41, while inch sizes vary between shapes such as 4:5, 3:4 and 2:3. Of the inch sizes we print, 28x40 is closest to the A shape.
How long does delivery take?
Allow 1–3 working days for printing, then 2–4 working days for free UK standard delivery or 2–5 working days for free worldwide delivery.
Sources (checked 29 October 2026): our Product Specifications, Delivery Info and Returns pages; the size options on the product pages linked above; and Wikipedia: ISO 216 for A-size dimensions and history.