Poster design

Making a Scientific Poster Accessible: Contrast, Color, Sizes

An accessible poster reads from a distance and for everyone: sufficient contrast, colorblind-safe choices, legible font sizes. The concrete guidelines, backed by sources.

July 4, 2026 · 6 min read

Quick answer: what makes a poster accessible?

An accessible poster is legible from a distance and to as many people as possible, including those who see color poorly. Three levers: strong contrast between text and background, colors that never carry information on their own (for colorblindness), and generous font sizes. These are not cosmetic details: they are the difference between a poster that gets read and one that gets ignored.

Contrast: the basis of legibility

A poster is read from one or two meters, often under poor lighting. Insufficient contrast between text and background makes it painful, or unreadable. Yale University library recommends checking that contrast with a dedicated tool, such as the Colour Contrast Analyser or the WebAIM Contrast Checker, rather than trusting your eye on a calibrated screen.

In practice: dark text on a light background (or the reverse), and a single strong accent color. Avoid colored text on colored backgrounds, and gradient backgrounds under text.

Colorblindness: never code by color alone

About one man in twelve sees certain colors poorly. If your message relies only on a red/green distinction, part of your audience will miss it. The rule, stressed by Yale: never code information by color alone.

Concretely:

In a chart, back up color with different patterns, hatching or shapes.
Label series directly rather than pointing to a colored legend.
Choose a colorblind-safe palette (tools like ColorBrewer offer "colorblind safe" sets).

Yale also points to David Nichols's "Coloring for Colorblindness" resource to test your colors.

Font sizes: legible from a distance

This is the number one cause of an unreadable poster. Yale's library gives concrete floors for a large-format poster:

Title: at least 72 pt (ideally around 158 pt).
Section headings: at least 42 pt (ideally 56 pt).
Body text: at least 24 pt (ideally 36 pt).
Captions: at least 18 pt (ideally 24 pt).

And a typographic recommendation: a sans-serif font for body and headings alike, more legible from afar. These guidelines echo conference rules (for example the CMGF, which asks for a title legible at 5 meters and body text at 1 meter).

Accessibility is also about structure

A readable poster is one that breathes: white space, two or three columns that guide the eye, a clear message. A wall of text, even well contrasted, stays hard. For structure, see our article on the IMRaD structure of a poster and, for a single-message approach, the Better Poster method.

How Folio Poster helps here

Respecting all these floors by hand is tedious. Folio Poster applies, by construction, font sizes adapted to the format, color themes designed for contrast, and a column layout that stays legible from a distance, from portrait to landscape. You focus on the content; the accessibility guardrails are handled. For the fundamentals, see the guide how to make a scientific poster.

In summary

Strong text/background contrast, checked with a tool (Colour Contrast Analyser, WebAIM).
Never color alone: add patterns, shapes, labels; use a colorblind-safe palette.
Minimum sizes (Yale): title 72 pt, sections 42 pt, body 24 pt, captions 18 pt.
Sans-serif and white space: a poster that breathes reads better.

Frequently asked questions

What is the minimum font size for a poster?
According to Yale's library: title at least 72 pt, section headings at least 42 pt, body at least 24 pt, captions at least 18 pt. These are floors: bigger is often better.

How do I choose accessible colors for a poster?
Ensure strong text/background contrast, never code information by color alone (add patterns or shapes), and use a colorblind-safe palette. Check with a contrast tool.

Serif or sans-serif font?
For a poster read from a distance, a sans-serif font is recommended, for body and headings alike. It stays legible from afar, unlike thin serifs.