Bionic Reading Converter

Bionic reading is a typographic technique that bolds the first portion of each word to create visual anchors for the eye. Readers tend to fixate on the bold prefix and let the brain fill in the remainder from context, the way you do when skimming a familiar passage. The method was popularised by a Swiss reading app in 2022 and has since become a common accessibility affordance — baked into Microsoft Edge's Immersive Reader, browser extensions, e-readers, and productivity tools.

Who benefits. Users with ADHD often report that bionic emphasis reduces the cognitive load of staying on the line. Readers with dyslexia sometimes find that it breaks the visual hunt for word boundaries. Time-pressed professionals scanning long documents use it to move through dense prose faster. The research is early and mixed — some studies show modest speed increases, others show none — but anecdotal adoption is strong.

How it works. Our converter wraps the first 30–60% of each word's letters in <b> tags. Short words (1–2 letters) are fully bolded; 3-letter words get 2 bolded; longer words scale with the ratio you choose. The original whitespace, punctuation, and capitalisation are preserved byte-for-byte. Non-Latin scripts (Cyrillic, Greek, CJK) also get the treatment because we match Unicode letter classes.

Copy options. "Copy HTML" gives you the raw <b>-tagged markup — paste into a blog post, CMS, or email HTML editor and the bolding survives. "Copy rich text" puts the formatted content on the clipboard in both HTML and plain text, so pasting into Word, Google Docs, Notion, or Slack preserves the bolding natively. Most modern browsers support the richer clipboard mode; older Safari falls back to HTML.

Tuning the ratio. 50% is the default from the original app. Drop to 30% for a lighter, less-distracting version (recommended for longer reads). Push to 70% when you need strong anchors (dense technical prose, fine-print review). Your preference varies with font choice too — serif fonts with more stroke contrast look cleaner at lower ratios; sans-serif handles higher ratios without looking blocky.

Accessibility notes. Bionic is a reading aid, not a universal improvement. Some readers with dyslexia find the alternating weight visually noisier, not less. Always offer a toggle when shipping bionic text on a public page, and keep a normal version as the default. Never apply it to content users are expected to transcribe or edit.

1. Paste text into the input. Any length.
2. Adjust the bold ratio — 50% is the classic default.
3. Preview in the reading pane with your chosen font size.
4. Copy rich text or HTML for use elsewhere.

• Configurable bold ratio (30–70%).
• Unicode-aware — works for non-Latin scripts too.
• Preserves original punctuation and whitespace.
• Rich-text and HTML copy modes.
• Runs entirely in your browser.