Readable Design for Everyone: Contrast, Text Size and Accessibility

Design principles8 min read · Updated: 03.11.2026

A design can look beautiful, but if customers can't read the phone number on a flyer or the prices on a menu, the advertising isn't working. Readability isn't a matter of taste. It comes down to a handful of measurable factors: contrast, text size, typeface, colour and wording. This guide sets out the specific thresholds we use when preparing files for print. It also shows how to make a design comfortable for older readers, people with low vision and those with colour vision deficiency.

How much contrast between text and background is enough?

The best benchmark is WCAG, the international standard for accessible digital content. Contrast is expressed as a ratio of the luminance of two colours. It runs from 1:1 (the same colour) to 21:1 (black on white). WCAG was written for websites, but the same thresholds work well on paper because the eye works the same way.

WCAG treats text of 18 pt and above, or 14 pt bold and above, as large text. Large text can get away with lower contrast because heavier letterforms are easier to pick out from the background. Always apply the stricter threshold to small text, contact details and prices.

• Black on white: 21:1, the gold standard for readability.
• Black on yellow: approx. 19.6:1, which is why it works so well in signage.
• Grey #767676 on white: approx. 4.5:1, the lightest grey that still passes AA.
• Red #FF0000 on white: approx. 4:1, not enough for small text.
• White on pale yellow: approx. 1.1:1, practically illegible.

How do you apply WCAG to print?

Contrast checkers work with RGB or HEX values, but print houses work in CMYK. Check the contrast using the RGB equivalents of your colours and build in some headroom, because the result on paper depends on the stock. Uncoated and recycled papers absorb ink and slightly dull the colours. Dark backgrounds print lighter and pale tints lose their punch.

Set small black text as 100% K, with no other inks mixed in. Rich black in small type creates coloured fringes and blurring with even the slightest misregistration. For reversed-out text, meaning white on a dark background, use a slightly larger and heavier weight. Ink from the background tends to fill in thin strokes.

• Don't place text directly over a busy photograph. Add a semi-transparent panel or choose a calm area of the image.
• Gloss varnish and glossy stock reflect light at certain angles. For menus and boards read under lamps, matt lamination works better.
• For reversed-out text, avoid serif typefaces with thin strokes and sizes below 8 pt.
• On white paper, grey text in print shouldn't be lighter than roughly 60–70% black. The exact threshold depends on the typeface and the stock.

Minimum text size in print

Type size is measured in typographic points. 1 pt is approx. 0.353 mm, so 12 pt equals a body height of approx. 4.2 mm. The actual size of the letters depends on the typeface, though. At the same point size, some fonts have noticeably taller lowercase letters than others. Treat the ranges below as a starting point and always judge a proof printed at 100% scale.

Food labels must also meet the EU food information rules, which also apply in UK law. Mandatory information must have a lowercase x-height of at least 1.2 mm. On packaging whose largest surface is under 80 cm², the minimum is 0.9 mm.

How large should lettering be on banners, roller banners and shop signs?

With large formats, what matters is the distance from which people read the text. A practical rule of thumb in outdoor advertising is approx. 1 cm of capital height for every metre of comfortable reading distance. With a bold, simple typeface and high contrast you can go slightly smaller. A thin or decorative font needs more.

Keep text to a minimum on banners and roller banners, because passers-by only have a few seconds. A headline, one benefit and your contact details are enough. Put everything else on a flyer.

Designing for older and partially sighted readers

As we age, the eye needs more light and struggles to tell similar shades apart. The lens also yellows, so pale blue and light grey text merges into the background. For this audience, increase body text to 12–14 pt and aim for 7:1 contrast. The same approach helps people with low vision and anyone reading in poor light.

The typeface matters as much as the size. Choose fonts with open letterforms, clearly distinct characters (I, l, 1 and O, 0) and a medium stroke weight.

• Avoid thin weights (light, thin), condensed typefaces and decorative scripts for informative text.
• Use leading of 120–150% of the type size, so roughly 14.5–18 pt line spacing for 12 pt text.
• Align text left rather than justifying it, as justification creates uneven gaps between words.
• Keep line length to approx. 45–75 characters, as longer lines tire the eyes.
• Use capitals only for short headlines, never for paragraphs.
• Group phone numbers into blocks, e.g. 07700 900 123, and give them a clear, prominent position.

Colour blindness: don't rely on colour alone

Colour vision deficiency mainly affects men, and confusing red with green is the most common form. People with this condition do see colour, but pairs such as red–green or brown–green can look almost identical. So the problem isn't colour itself. It's information conveyed by colour alone.

The simplest test is to convert your design to greyscale. If the headline, the price or a label still stands out, the design is safe. Design software also offers colour blindness simulation, for example in the proof colours settings.

• Don't put red text on a green background, or vice versa.
• Back up menu labels (vegetarian, spicy, gluten-free) with an icon or abbreviation, not just colour.
• Make sale prices stand out through size, bold type or a box as well.
• On charts and maps, add labels, patterns or different marker shapes.
• Safe combinations include dark navy with yellow and blue with orange, provided they differ in lightness.

Plain language and checking your design before print

Readability is also about language. Short sentences, familiar words and one main message per piece mean everyone can understand the text, including people reading in a second language. Write in the active voice: rather than 'orders are processed', write 'we process your orders'. Give numbers, times and prices as figures.

Before sending to print, print the design at 100% scale on an ordinary office printer. Then read it from the distance at which it will be viewed. If you order a design from plakaty.shop (wielkareklama.eu studio), the text is checked automatically. Always read phone numbers, addresses and opening hours through yourself as well.

• One idea per sentence, ideally no more than about 15 words.
• Use full, everyday words rather than industry jargon or abbreviations.
• Put the most important information at the top and the detail below.
• Include a clear call to action: call, visit, order.