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Bionic Reading Converter

Convert text to bionic reading format by bolding the first few letters of each word to guide the eye and boost reading speed.

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About this tool

The Bionic Reading Converter reformats text by bolding the first portion of each word. The Bold fraction slider (20% to 70%, default 40%) sets what share of each word's letters is bolded, rounded up, with at least one letter per word. This technique creates artificial fixation points that some readers say help the eye move faster across lines. Readers who struggle with focus, or simply want to skim long articles, sometimes find bionic reading helpful. The preview updates as you type or move the slider, and Copy as HTML copies the result with <strong> tags so you can paste it into a web page or HTML-aware editor. Words are detected as runs of the plain letters A–Z, digits and underscores, so accented letters split a word and non-Latin scripts are left unbolded.

Why use it

  • Adjustable fixation ratio adapts to different reading styles and preferences.

  • Preview renders in real time so you can find the best setting quickly.

  • Outputs valid HTML with <strong> tags, ready to paste into web editors.

  • Runs entirely in your browser with no account or extension needed.

  • Generates clean HTML with semantic <strong> tags for accessibility and SEO.

  • No subscription or paid tier — fully free unlike commercial bionic-reading apps.

How to use

  1. Paste your text into the Input text box.
  2. Move the Bold fraction slider (20%–70%) to control how many leading letters are bolded.
  3. Preview the bionic reading output in the Bionic preview box; it updates as you type.
  4. Click Copy as HTML to copy the formatted output with <strong> tags.
  5. Experiment with different fractions to see which feels best for your reading style.
  6. Paste the HTML into a CMS, blog editor or HTML file that renders tags.

When it helps

  • Reformatting long articles or reports to read them more quickly.
  • Converting study materials for learners who benefit from visual reading aids.
  • Experimenting with reading speed techniques before committing to a paid app.
  • Creating accessible reading formats for users with attention or focus challenges.
  • Helping ADHD or dyslexic readers focus on textbook chapters.
  • Creating accessible reading versions of newsletters or blog posts.

Examples

Short sentence

Input

The quick brown fox jumps over the lazy dog.

Expected result

<strong>Th</strong>e <strong>qu</strong>ick <strong>br</strong>own <strong>fo</strong>x <strong>ju</strong>mps <strong>ov</strong>er <strong>th</strong>e <strong>la</strong>zy <strong>do</strong>g.

Article paragraph

Input

Bionic reading helps focus.

Expected result

<strong>Bio</strong>nic <strong>rea</strong>ding <strong>he</strong>lps <strong>fo</strong>cus.

Single word

Input

implementation

Expected result

<strong>implem</strong>entation

Tips

  • Start with the default 40% and adjust from there; most readers settle between 30% and 50%.
  • For dense academic text, lower the fraction to 30% to keep more text un-bolded and easier to scan.
  • For light reading or social posts, 50% makes the bionic effect more pronounced.
  • Pair with the Reading Time Calculator to estimate how long a converted article takes to read.
  • Paste the copied HTML into an HTML view or code editor; pasting it into a word processor as plain text shows the <strong> tags literally.

Frequently Asked Questions

Is there scientific proof bionic reading improves speed?
Evidence is mixed. Some readers report faster, more focused reading; others see no benefit. It is most useful for individuals who find it helpful in practice.
What is the bold fraction?
The Bold fraction slider controls what share of each word's letters is bolded, from 20% to 70% in 5% steps. At 40%, a five-letter word gets ceil(5 × 0.4) = 2 bold letters.
What format does the output use?
The output uses HTML <strong> tags around the fixation letters. You can paste it into any HTML editor or rich-text tool.
Does it work with punctuation?
Yes. Punctuation attached to words (periods, commas) is handled so only actual word letters are processed.
Can I use it with non-English text?
Only partly. Words are matched with the ASCII letters A–Z, so an accented letter breaks a word into pieces (naïve is bolded as n + aï + v + e) and Cyrillic, Greek, Arabic or CJK text is not bolded at all.
How does the algorithm decide which letters to bold?
It multiplies the word length by the bold fraction and rounds up, with a minimum of one letter. At the default 40%, one- and two-letter words get one bold letter, three- to five-letter words get two, and implementation (14 letters) gets six.
Can I export to plain text instead of HTML?
Bold formatting needs HTML or rich text. Copy plain copies your original input without any bold, which is useful if you only want the unformatted text back.
Should I paste HTML-like text into it?
No. The input is inserted into the preview as HTML without escaping, so tags in your text are rendered or broken instead of being shown. Paste plain prose only.

Explore the category

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Glossary

Bionic reading
A text-formatting method that bolds the initial letters of each word to create artificial fixation points for faster reading.
Fixation point
The position where the eye stops momentarily while reading; bionic reading aims to standardize these stops.
Saccade
The rapid eye movement between fixations as you read across a line of text.
Fixation ratio
The fraction of each word's letters that are bolded — typically 0.3 to 0.5 in bionic reading systems.
Reading speed
Words per minute you process while comprehending text; varies with content complexity and reading aids.
Semantic HTML
HTML that conveys meaning through tag choice (<strong> for emphasis) rather than just presentation (<b> for bold).
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