Letter, word and line spacing

See it for yourself

Three sliders, one paragraph. The WCAG 1.4.12 floor is marked on each.

Reading should not be hard work. Good tools meet you where you are: they change the page instead of asking you to change. Try the controls and watch this paragraph respond — nothing you do here leaves your browser. Crowded letters lean on their neighbors; spaced letters stand alone. Somewhere in the middle is the setting your eyes have been asking for.

How it works

Letters need elbow room

When letters sit very close together, your eyes see them but your visual system struggles to keep them apart — each letter interferes with recognizing its neighbors. Researchers call this crowding. Every letter needs a small pocket of clear space to be read cleanly, and the pocket grows the further a letter sits from the exact spot you are looking at. Extra letter spacing gives each letter its pocket back.

Words need clear edges

Word spacing does a different job: it marks where one word ends and the next begins. Open up the letters without opening up the words and the gaps inside a word start to rival the gaps between words, so the line flattens into a stream of letters with no landmarks. The two settings travel together — which is why the demo above gives you both.

Lines need a track

Line height is for the trip back. At the end of each line your eyes sweep left to find the start of the next one, and when lines sit tight, that sweep lands on the wrong line more often than you would guess — you reread a line, or lose one entirely. Extra height gives the return sweep a track to follow. Slide the third control above and watch the paragraph settle.

Where it came from

The idea is older than the web. In the 1970s, vision research by Bouma mapped what became known as crowding zones — the clear space a letter needs before its neighbors start to interfere, and how that space grows toward the edges of your vision. It was lab science about how eyes work, not advice about reading, but it laid the ground for everything that followed.

The result that made it practical came in 2012, when Zorzi and colleagues published a study in PNAS with a finding you can act on: children with dyslexia read faster and made fewer errors when ordinary text was set with extra-large letter spacing. No training, no special font, no waiting — the same children and the same words, with more space between the letters. Few findings in this field are that direct.

The web caught up. WCAG, the accessibility standard websites are measured against, now says a page must keep working when a reader overrides its spacing — up to letter spacing 0.12em, word spacing 0.16em, and line height 1.5. Those are the floors marked on the demo above. Spacing went from a lab result to something you are entitled to change on any well-built page.

Who it helps — honestly

Here is the short version: spacing is the best-evidenced typography change there is. Dyslexia fonts show mixed results in studies — the honest picture is on our OpenDyslexic page — but extra space helped children with dyslexia read measurably faster and more accurately in controlled research. And because crowding affects every reader to some degree, most people get something out of it, dyslexia or not.

It is a dial, not a switch. Push letter spacing far enough and words stop reading as words — they break apart into strings of loose letters, and reading slows down again. The useful range sits in the middle, and it varies from person to person, which is why the demo gives you sliders instead of one "correct" setting.

And you do not need a special font to benefit. Spacing works with any font — the one you are reading now, the default on your favorite site, or a dyslexia font if you prefer one. Pair it with a comfortable line length and you have most of what makes text feel calm. Try the sliders above on real text and stop where your eyes go quiet.

Try it in Helperbird

Helperbird brings these tools to any website, PDF, or Google Doc — no copying text anywhere, and nothing you read leaves your browser.

Letter & word spacing Open up any page's spacing without touching the site itself.

Step-by-step: How to change letter spacing on any website · How to change word spacing on any website

Questions people ask

What is visual crowding?

When letters sit very close together, your visual system struggles to keep them separate — each letter interferes with recognizing its neighbors. Crowding affects everyone, and research suggests readers with dyslexia feel it more strongly.

Does letter spacing help dyslexia?

It is one of the best-supported typography changes there is. A well-known 2012 study found children with dyslexia read faster and made fewer errors with extra-large letter spacing — with no training, no special font, only space.

Can spacing be overdone?

Yes. Past a point, extra letter spacing starts breaking words into strings of unrelated letters and reading slows again. That is why the demo has a range rather than one "correct" value.