TEXT SIZE, INTERLINE AND SPACING

Let’s start with the text size in general. I’ve increased the x-height of Dyslexie Font slightly to allow for more space within the letter. This works better for people with dyslexia. An advantage is that if you use this size as the standard, you don’t have to adjust the text separately for dyslexic readers.

The general guideline for print or printed text is simple and usually the most readable:

• Young children (5-6 years): 16 pt
• Children (7-8 years): 14 pt
• Children (9-11 years): 12 pt
• Older children and adults: 10 pt

You can deviate from this. Older people with poorer vision, for example, go to 11 or 12 pt. Some children aged 7-11 with extensive reading experience prefer a point smaller. Some adults also prefer 9 pt for reading text. So you can also follow this with Dyslexia Font, there is nothing wrong with our eyes.

A ‘pt’ (point) is a standard measurement in typography and is equal to 0.3528 mm. This allows you to measure the x-height on paper with a ruler and thus determine the font size used. Each millimeter is approximately 3 pt (1.0584 mm, to be precise, if you’re interested).

This unit of measurement dates back to the 18th century, to the era of lead type. Printers needed a universal unit so that all printers could use the same size.

This system worked well until around 1972, when Xerox created the first bitmap fonts. In 1984, Steve Jobs—who had taken calligraphy lessons—launched the Macintosh computer. This computer, for the first time, added a wide variety of fonts to the general public.

This, however, presents a fundamental problem. Fonts have always been designed and specified in points. Even with digitalization, this remains the standard. However, the screen on which the text is displayed works in pixels.

Moreover, pixels were large in the 1970s and 1980s compared to today. And screen resolution has improved enormously. Where you used to be able to count pixels from a distance, an individual pixel is now often impossible to distinguish with the naked eye.

Each manufacturer uses different techniques for pixel density (DPI/PPI). Screens are indicated by a resolution such as 1920×1080, or multiples thereof (2K, 4K, 8K). This only indicates the number of pixels, not how small or close together they are.

The result? A 14-point font was large and legible on a 1920×1080 screen in 2014. However, on a modern 4K screen with a much higher pixel density, that same 14-point font is too small and unreadable, which is why 16 or 18 pt is now often chosen for body text. At the same time, there are small screens (such as smartphones) with an extremely high pixel density, which we also hold closer. On those, 14 or 16 pt is often sufficient.

The conclusion is that fixed point sizes no longer work. You should be looking much more at responsive text, which automatically adjusts to the screen size, pixel density, and reading distance.

DEVELOPERS SCALE SMARTER FOR TRUE ACCESSIBILITY

Many developers opt for linear font size increases up to 42pt, but miss the mark. For approximately 80% of the population, the steps in a linear line are far too large; they need subtle, small adjustments.

Users with severe visual impairments are a relatively small group who often already rely on external aids. The greatest benefit lies in the nuance. By opting for an exponential increase—small steps at the beginning and larger jumps at the end—you optimally serve everyone.

An effective sequence would look like this: 14 – 15 – 16 – 17 – 18 – 19 – 20 – 21 – 22 – 28 – 34 – 42pt

This also applies to steps with spacing and leading.

INTERLINE AND SPACING

The space around that letter. Many people think that simply making the letters larger makes text more readable, but experience shows that the space between letters and lines is just as important.

Good white space makes text feel “larger” and “more relaxed,” without actually having to increase the font size.

INTERLINE: FOCUS BETWEEN THE LINES

Line spacing (line spacing) is the white space between sentences. When lines are too close together, it’s difficult to focus on the line of text being read. The bottom of the letters on the top line and the top of the letters on the bottom line then encroach on your focus area as you read. This is distracting and makes it difficult to retain the sentence.

The “Selection Method” A practical way to check if your line spacing is correct is to select the text on your screen (so that a colored or black bar appears behind it).

• Increase the line spacing until a thin strip of white space appears between the selection bars (see image).
• The clean, straight lines of the selection immediately show you whether the lines are “choking” each other or whether they have room to breathe.

SPACING PREVENTING THE CROWD EFFECT

Where leading creates a sense of calm between lines, spacing (tracking) focuses on the detail: the space between the letters themselves.

When I designed the Dyslexia Font in 2008, ideal spacing was one of the most important foundations I incorporated directly into the font. In 2012, this was scientifically substantiated by an Italian university; their research on reading improvement in dyslexics arrived at exactly the same ideal spacing.

Why extra space helps:

Prevents merging: Many readers (and especially people with dyslexia) experience the crowding effect. Letters appear to flow or merge into one another, especially with longer words.

Better identification: By giving the letters a little more space, the brain can more quickly identify the unique shape of each letter.

With ‘spacing 40’, you’ll see that letters are given their own space, which minimizes the crowding effect.

Pushing the boundaries: Are you using a standard font? Then a spacing of 30 or 40 is often sufficient. Be careful, though: if you use too much space, the text will start to “swim.” The letters then lose their connection, and the brain no longer recognizes the word as a whole.

SPACE ON THE PAGE
If you use too much space on your page, which is often true for printed pages, you can correct the space by making other elements smaller. For example, consider adding a blank line between paragraphs. Often, a “half-enter” is sufficient. This gives the reader a clear resting point and a visual block. You can also make the font itself a point smaller, as it still has enough space around it to visually appear larger. This often results in the same length as text without any adjustments, while still resulting in a more readable text.