How to design a poster

To design a poster, work from the distance it will be read. Decide where people will stand, make the headline and one image large enough to catch them from across the room, size the key facts, the date, the time and the place, to read from about three metres, and leave the fine detail for people who walk up close. Then choose colours with strong contrast and print at a size where that type holds up. At three metres, the UC Davis Undergraduate Research Center’s poster guide puts legible text at about 48 point, which is why a good poster has so few words.

The table under this article sets out minimum text sizes by viewing distance, drawn from three university and conference poster guides.

Start from the distance

A flyer is picked up; a poster is walked past. That single difference decides the design.

Stand where the poster will hang and look at the wall from where people will actually be: the footpath outside a window, the far side of a corridor, the queue at a counter. That distance sets the size of everything else. UC Davis’s guide gives a simple ladder: text legible from about 6 feet needs 30 point, from 10 feet 48 point, from 12 feet 60 point and from 14 feet 72 point.

The concert flyer is three designs for one fictional Friday night at a live music venue, and each is built for a different distance. The lineup poster goes up around the neighbourhood with the date, doors at 8pm and the age limit. The date poster goes behind the bar and lists the three acts against their set times, 8.30, 9.40 and 10.45. The full bill goes online for people deciding whether to buy. Same event, three reading distances, three designs.

One image, one headline

From across a room, a poster is an image and a few words. Choose one image that shows the event or the result, and one headline that says what it is.

Nielsen Norman Group’s principles of visual design describe scale as using relative size to signal importance: the most important element is the largest, because big things are noticed. On a poster, that is the headline or the image, never both at the same size competing for attention.

The concert date poster makes a useful choice here. It drops the crowd photograph used on the other two designs and lets the three numbered acts carry the page, because behind a bar the useful fact is when each band plays, not what the crowd looks like.

Type size by distance

Set three levels of type, each sized for its own distance.

1. The headline, for the furthest distance: from 72 point for a poster read across a corridor, to 85 to 120 point for a title meant to stop people across a room, as the CASRAI poster guide suggests.
2. The key facts, for about three metres: 48 point or more for the date, the time and the place.
3. The details, for people who walk up: 24 to 32 point for a web address, terms or a price breakdown, the body text range the same guide gives for readers at 3 to 4 feet.

BAPEN’s poster guidelines express the same idea in millimetres rather than points: for a poster readable from 1.5 to 2 metres, capitals should be at least 5 mm high and the title letters at least 2.5 cm. Measuring a printed letter with a ruler is a quick check that needs no software.

The fun run flyer shows the three levels in practice. Its poster design, built for a shop window, carries the event name and the three distances in the hero, a wide foreshore photograph, then three large rows of distance, start time and fee, and nothing below them.

Contrast and colour at a distance

Distance lowers apparent contrast, and so do glass, glare and evening light. Choose a light background with dark text or a dark background with light text, and avoid pale colour on pale colour. UC Davis’s guide recommends two or three colours for a poster and warns that colours can appear differently on screen than in print.

Test contrast properly rather than by eye. The WCAG minimum of 4.5 to 1 for normal text is a sensible floor for a poster too, and the headline can use a bolder colour as long as it still stands clear of the background.

Choosing the print size

The A sizes share one shape: each is the one below doubled in area, with the same proportions. That means a design made on an A4 canvas scales to A3, A2 or A1 with nothing cropped, and every text size grows with it. Text set at 24 point on A4 becomes about 34 point on A3 and 48 point on A2, which is the three metre size in the table.

Resolution thins as the poster grows, but posters are seen from further away. An A4 design exported at 2480 by 3508 pixels is about 212 pixels per inch at A3 and about 150 at A2. What DPI a poster needs explains why around 100 pixels per inch at full size is enough for something read from a metre or more.

Check where it will hang before choosing. The City of Sydney’s free poster pillars take one poster per person up to A2, and a shop window rarely fits more than A3.

Posters that people walk up to

Not every poster is read in passing. A conference board is approached, and the reader stays. BAPEN’s guidelines note that the average reader spends one to two minutes at a poster and often reads the conclusions first, and suggest placing the conclusions at eye level and laying the board out in two or three columns read top to bottom.

That changes the balance. The clinical trial poster is an A0 board with a full study title across the top, three key numbers with their confidence intervals, a participant flow and three charts, far more than an event poster could carry, because its readers are standing within arm’s length. The distance ladder still applies to its title and key numbers, which have to pull people across the room first.

An event poster is closer to the open house flyer: a few facts, one of them repeated, for someone who will give it seconds.

Common mistakes

• Flyer copy on a poster. A paragraph that works in a hand is unreadable from three metres.
• The date in small type. It is the fact people most need, so it should be the second largest thing on the page.
• A busy photograph behind text. Contrast varies across the image, so some words disappear.
• Two images of equal size. Neither wins, and the eye has nowhere to start.
• Designing at arm’s length. Always check a print from the real viewing distance.

Build it

For an event or shop poster, design on the A4 portrait canvas, 1240 by 1754 pixels, and ask the printer to scale the PDF to A3 or A2; the export is 2480 by 3508 pixels, with no bleed, crop marks or CMYK conversion, so say that when ordering. The guide to choosing your flyer’s template, theme and size shows where the format is set.

For a conference or research poster, the poster tab has 40 A0 layouts, 20 portrait at 1656 by 2340 pixels and 20 landscape at 2340 by 1656, exported at twice the canvas, which is about 100 pixels per inch at full A0. Poster generation bills at twice the flyer rate. The A0 poster size page covers the canvas, and research poster font size sets out type sizes for an A0 board, which is read up close for much longer than an event poster.