Bionic Reading was popularised by a 2022 viral demo from a Swiss company. The idea: human reading speed is bottlenecked by the eye’s saccadic jumps between words, and bolding the leading letters gives the eye a clearer landing target — increasing reading speed without sacrificing comprehension. Some readers describe it as a noticeable boost, especially for skimming long technical articles; others call it visually distracting and slower. Like all reading aids, mileage varies.
Our bionic reading converter applies the formatting to any text you paste, with a slider for fixation ratio (how many letters to bold). Output is rich HTML you can copy-paste into a Doc or Notion, or export as PDF/HTML for printing. The conversion runs entirely in your browser — your text never leaves your device. This guide explains how the algorithm works, the research-vs-marketing claims, and when bionic formatting is genuinely useful (and when it gets in the way).
How the formatting works (the algorithm)
| Word length | Letters bolded (default) | Example |
|---|---|---|
| 1–3 letters | 1 | an, the, it |
| 4 letters | 2 | that, from |
| 5–6 letters | 2 or 3 | strong, beyond |
| 7–10 letters | 3 or 4 | fixation, reading |
| 11+ letters | 4 or 5 | technology, cognition |
The fixation ratio slider lets you adjust this aggressiveness. Lower (e.g., bolding only ~30% of each word) is subtler; higher (~60%+) is heavier and may feel cluttered. The original Bionic Reading uses ~50% by default.
Does it actually help reading speed?
The marketing claim is “up to 200% faster”. The peer-reviewed research is more modest. A 2022 study by the University of Cambridge found no statistically significant reading-speed improvement across 200 subjects. Independent psycholinguists have pushed back on the broader claims. So the honest answer: bionic reading doesn’t make most people faster.
What it does seem to help with, anecdotally:
- ADHD readers: some users with ADHD report that bionic format helps them maintain focus on long passages — bold lead-letters work as visual anchors that re-engage attention.
- Skimming. When the goal isn’t full comprehension but skimming for keywords, bionic format helps pull the gaze across faster.
- Cognitive load on dense material. For some readers, the visual structure makes paragraph-shaped walls of text less daunting.
- Dyslexic readers. Reports are mixed — some dyslexic readers find it helpful, others find the visual noise harder to parse.
If you’re considering bionic formatting as an accessibility feature, test with the actual readers it’s meant to help — don’t assume it works for everyone.
How to convert text to bionic reading
- Open the bionic reading converter
- Paste your text in the input
- Adjust the fixation slider (default 50% — half the letters of each word bolded)
- Pick output format: HTML (paste into Doc or Notion), Rich text (clipboard), or PDF
- Click Copy or Download
The HTML output (and why rich-text matters)
Plain text can’t carry the bold formatting; you need rich HTML. The converter outputs HTML like this:
<p>
<strong>Bo</strong>ld
<strong>th</strong>e
<strong>fir</strong>st
<strong>hal</strong>f
<strong>of</strong>
<strong>ev</strong>ery
<strong>wor</strong>d.
</p>Pasting this into Notion, Google Docs, or any rich-text editor preserves the bold formatting. Pasting into a plain-text editor strips the HTML and you get the original text without bolding. Use the “Copy as Rich Text” button in our tool — it puts both HTML and plain-text versions on the clipboard, and the destination app picks whichever it supports.
Common gotchas
- Hyphenated words become odd. “Self-aware” with bionic formatting becomes “Self-aware”, which most readers find harder, not easier. Our converter has an option to skip words shorter than 4 characters and to treat hyphenated words as a unit.
- Numbers and code snippets shouldn’t be bionic-formatted. “404 not found” with bolding becomes confusing. The converter detects numeric words and code-fenced text (markdown
`code`) and skips them by default. - Doesn’t work in pure plain text. Email-only readers, plain-text terminals, and any non-rich-text destination strip the formatting. Use HTML or PDF for digital sharing.
- Don’t mass-convert your reading list. The format works for some content (dense technical articles) and against others (poetry, fiction, copy-edited prose where typography matters). Convert per-document, not by default.
- Accessibility considerations. Bold text increases visual noise for some users with low vision or specific reading disabilities. Always offer a toggle to view the original — never force bionic formatting on readers without consent.
- Trademark issue. “Bionic Reading” is a trademarked name owned by Bionic Reading AG. Open-source equivalents go by names like “OpenDyslexic Reading” or just “fixation reading” to avoid the trademark — our tool uses the term “bionic reading” as the descriptive technique name, not as the brand.
When NOT to use bionic reading
For literary or carefully-written prose where the rhythm of the language matters, bionic formatting interferes with the reading experience the author intended. For poetry — never use it; the visual structure of the poem is part of the meaning. For language learners reading in a foreign language, bionic formatting can confuse word-segmentation as you’re still building your mental dictionary. For ebook readers (Kindle, Kobo), most don’t preserve rich-text bolding consistently — convert just before reading, not as a permanent storage format. For accessibility certifications (WCAG), bold-heavy content can fail readability thresholds.
Frequently asked questions
Does bionic reading actually make me read faster?
Studies are mixed. A 2022 Cambridge study found no significant speed improvement across the general population. Anecdotally, some readers — especially those with ADHD — report subjective benefit. Try it on your own typical reading material and decide.
Can I use this for ebooks?
Yes — convert a chapter to PDF or HTML, then transfer to your ebook reader. Most readers preserve bold formatting in EPUB and PDF. Kindle’s older firmware sometimes drops bold; test on your specific device.
Is this the same as the trademarked “Bionic Reading”?
It’s the same technique. “Bionic Reading” is a trademark of Bionic Reading AG; we use the term descriptively (like “spell check” or “track changes”). The algorithm is straightforward and unpatented; many open-source implementations exist.
Can I customise how aggressive the bolding is?
Yes — the fixation ratio slider goes from very subtle (~30% of each word bolded) to heavy (~70%). Default is 50%, matching the original tool. Lower ratios are easier on the eyes; higher ratios produce stronger anchor points for skimming.
Is my text uploaded?
No. The converter runs in your browser. Pasted text never leaves your device — useful when converting drafts, internal documents, or anything you’d rather not share with a third party.
Does it work with non-English text?
Yes — the algorithm is language-agnostic; it bolds the first portion of each space-separated word. It works with any language that uses spaces between words (most European languages, Vietnamese, etc.). Languages without word spaces (Chinese, Japanese, Thai, Korean) need a tokeniser before formatting; our tool detects and warns when input lacks word boundaries.
Related tools and guides
- Bionic Reading Converter
- Text to Handwriting Converter
- Google Fonts Pair Finder
- Character Counter
- All text tools