Poster Size Guide: A0, A1, A2, A3 and A4 Explained

Quick answer: For an academic conference, A0 (841 × 1189 mm) is the most common size, with A1 the next most common. For a school classroom or noticeboard, A3 or A2 is usually right. Corridors and halls need A1 or A0, and A4 suits small spaces such as doors, desks and toilet cubicles. Always check a conference’s poster rules first, because the organisers set the size.

Choosing the wrong poster size is an easy mistake to make. A poster that is too small gets ignored, while one that is too big for the board will not fit. This guide explains every A-size from A4 to A0, what each one is best for, and how far away it can be read. It covers academic posters for conferences and ready-made posters for schools.

Poster sizes at a glance

A sizes follow the international ISO 216 standard. Each size is exactly half the area of the one above it. So an A1 poster is two A2 sheets side by side, and an A0 is two A1s.

A0 poster size: the conference standard

A0 measures 841 × 1189 mm, about the size of a standard poster board panel. It is the default size at most UK and European academic conferences, usually in portrait. That size gives you enough room for a title, background, methods, results with graphs, a conclusion and references, all at a font size people can read from a metre or two away.

A0 is also the best size for a school entrance hall or sports hall, where a poster has to catch attention from across a large room. You can order academic posters through our A0 poster printing service.

A1 poster size: corridors and smaller events

A1 is 594 × 841 mm, half the size of A0. Some conferences, poster competitions and departmental research days ask for A1 because it lets them fit more posters into a smaller space. It is also a good size for school corridors, where people walk past at a distance of one to two metres. See our A1 poster printing page for academic posters.

A2 poster size: the all-rounder

A2 is 420 × 594 mm. It is big enough to be read from a few steps away but still fits on most classroom and staff room noticeboards. Students often use A2 for coursework displays and group projects. For schools, A2 is a safe choice for a main message in a classroom or library. More details are on our A2 poster printing page.

A3 poster size: classrooms and small boards

A3 is 297 × 420 mm, twice the size of a sheet of printer paper. It works well inside a classroom, next to a whiteboard, or on a small noticeboard where people stand close. A3 is also a popular size for putting up a full set of posters, such as all four designs in a range, without taking over a whole wall. For academic posters, see our A3 poster printing page.

A4 poster size: close-up reading

A4 is 210 × 297 mm. Use it where people will be within arm’s length, such as on the back of a toilet door, beside a computer in an ICT suite, on a desk, or inside a planner. A4 is the cheapest way to repeat one message in many places across a school. For academic handouts, see our A4 poster printing page.

How far away can each size be read?

Readability depends on the font size more than the paper size, but bigger paper lets you use bigger text. As a rough guide for posters with a short, bold headline:

• A4: best read from under 1 metre
• A3: about 1 to 2 metres
• A2: about 2 to 3 metres
• A1: about 3 to 4 metres
• A0: about 4 metres or more for the headline, and 1 to 2 metres for body text

For an academic poster, a title of 72 to 100pt and body text of at least 24pt on A0 keeps it readable from a comfortable distance. Our guide to making an academic poster covers fonts and layout in more detail.

Choosing a size for a school

Think about where the poster will go and how close people will be:

• Entrance halls and receptions: A1 or A0, so visitors and pupils see it straight away.
• Corridors: A2 or A1 at eye level, because people read while walking.
• Classrooms: A3 or A2 near the board or reading corner.
• Toilets, doors and ICT suites: A4 or A3, where people are close.
• Staff rooms: A3 or A2 on the noticeboard.

Many schools mix sizes: one large poster in a main area and smaller copies in classrooms. All of our ready-made school posters, such as the anti-bullying posters and online safety posters, come in every size from A4 to A0 at the same prices.

Choosing a size for a conference

1. Read the conference rules. The organisers will state the size and orientation. If they give a board size instead, choose the largest A-size that fits with a small margin.
2. Check portrait or landscape. Most boards suit A0 portrait, but some events ask for landscape.
3. Do not scale up a small file. If you designed in A1 and need A0, check that images are still sharp. We recommend 300dpi at the final printed size.
4. Allow time for delivery. Free standard UK delivery takes 2 to 3 working days. If time is short, Next Day delivery is £9.99. Order Before 12PM for Next Day delivery.