UtilibyWritten by the Utiliby editorial team · Last updated October 13, 2026 · Rules and formulas reviewed October 2026
What this free bionic reading converter does
This free online bionic reading converter turns ordinary text into text where the first letters of each word are bold. Paste an article, an email, a school reading or a long document, and you instantly get a version that gives your eyes a series of bold anchor points to follow. You can choose how much of each word is bold, how often to bold words, and the font, size, spacing, line width and colours, so you can build a layout that suits you.
Beyond conversion, the tool includes a reading ruler that highlights one line at a time, a speed reader that flashes words at your chosen pace, and a readability report with a Flesch Reading Ease score, grade level and reading time. It runs in your browser, so your text stays private. Bionic Reading is a registered trademark of Bionic Reading AG; this tool is independent and not affiliated with that company.
How to use the bionic reading converter
- Paste your text. The converted text appears as you type.
- Set the fixation. The slider decides how much of each word is bold. Start near 50%.
- Choose the rhythm. Bold every word, or every second or third word. Skip very short words if you find them distracting.
- Pick a comfortable layout. Change font, size, line height, letter and word spacing, line width and theme. Cream, soft blue and dark themes reduce glare.
- Use the ruler. Tick Reading ruler and move your pointer or finger down the text.
- Copy or save. Copy as HTML or Markdown, download a styled HTML page, or print to PDF.
- Try the other tabs. Speed reader shows the words one at a time; Readability tells you how easy the text is.
Does bionic reading work? What the evidence says
The idea behind bionic reading is that the eye does not need to read every letter of every word. Skilled readers recognise words from their shape and first letters, so bold fixation points may help the eye jump through the text. Supporters report that it makes dense text feel lighter and easier to start. Some people with attention difficulties say it helps them keep their place.
The research so far is limited and not encouraging for broad claims. Small experiments that compared plain text with bionic-style text found no clear improvement in speed or comprehension for the average reader, and some readers were slower. That does not mean it is useless for you. Reading comfort is personal, and a formatting change that you like and that keeps you reading is worth having. Treat bionic formatting as one option in a toolbox of reading aids, not as a cure or a guaranteed speed boost.
| Adjustment | Why it can help | Evidence |
|---|---|---|
| Larger text and more line spacing | Reduces crowding, easier on tired eyes | Well supported |
| Shorter lines (about 50 to 75 characters) | Easier to track from line to line | Well supported |
| Clear sans-serif or dyslexia-friendly fonts | Distinct letter shapes | Mixed, depends on the person |
| Tinted backgrounds | Less glare | Mixed |
| Bionic bolding | Visual anchor points | Limited, mixed |
| Reading ruler | Keeps your place | Popular, some support |
Settings explained
- Fixation (bold share). The share of each word that is bold, from 10 to 90%. A one-letter word is bold completely; a ten-letter word at 50% has five bold letters.
- Bold every N words. A larger number gives more plain words between bold anchors, which some people call a faster rhythm.
- Short words. Skip one-letter or one-to-two-letter words such as a, I, of and to if the bold on tiny words feels busy.
- Font and size. The dyslexia-friendly option uses OpenDyslexic or Lexend when installed, then a clear fallback. Verdana and Tahoma are wide and open, and are often recommended.
- Line height and spacing. A line height of 1.5 to 2 and a small increase in letter or word spacing can help. Do not overdo it.
- Line width. About 60 to 70 characters per line is common advice.
- Theme. Light, cream paper, soft blue, dark and high contrast yellow on black.
The reading ruler and line focus
Line focus tools highlight the line you are reading and soften the rest. Many readers use a card or a finger on paper; the reading ruler does the same on screen. Tick the option, then move your mouse or drag your finger over the text. The band is exactly one line high at your chosen size and line spacing. It is useful for dense text, tables of data and for readers who lose their place when lines wrap.
Speed reading with the word-by-word reader
The Speed reader tab uses rapid serial visual presentation: one word (or a small group) appears at a time in the same place, so your eyes do not move across the line. The red letter marks the optimal recognition point, roughly one third of the way into a word, where readers are fastest at recognising it. Pauses are added after commas and sentence endings.
| Speed | Words per minute | Typical use |
|---|---|---|
| Slow | 150 | Careful reading, complex text |
| Average | 230 to 260 | Normal silent reading of non-fiction |
| Fast | 300 to 400 | Skimming familiar material |
| Very fast | 500 or more | Scanning; comprehension falls for most people |
Studies of speed reading find a trade-off between speed and understanding. Use this mode to skim or to practise pace, and slow down for anything you need to remember or act on.
Readability scores explained
The Readability tab calculates the Flesch Reading Ease, Flesch-Kincaid grade level, average sentence length, long word share and reading time. The Flesch Reading Ease formula is 206.835 − 1.015 × (words per sentence) − 84.6 × (syllables per word). A score of 60 to 70 is considered plain English that most adults can follow easily; scores under 30 are very difficult.
| Flesch score | Level |
|---|---|
| 90 to 100 | Very easy, about 5th grade |
| 80 to 90 | Easy |
| 70 to 80 | Fairly easy |
| 60 to 70 | Plain English |
| 50 to 60 | Fairly difficult |
| 30 to 50 | Difficult, college level |
| 0 to 30 | Very difficult, graduate level |
The syllable count is a quick English heuristic and can be off by a few percent. Use the scores to compare drafts, not as exact values. Shorter sentences and everyday words help every reader more than any font trick.
Who uses bionic reading formatting
- Students working through long readings and study notes.
- Professionals skimming reports and long emails.
- People with ADHD or reading fatigue who find a visual anchor helps them start and keep going.
- People with dyslexia who combine it with larger type, wider spacing and a clear font.
- Writers and editors checking how a draft reads in a different layout.
- Accessibility teams demonstrating reading customisation options.
Tips for more comfortable reading
- Compare the same paragraph in plain and bionic form for a minute each and see which feels easier.
- Use a lower fixation (30 to 40%) if the bold is distracting.
- Increase line height before you increase letter spacing.
- Take breaks and use the dark or cream theme in the evening.
- Break long paragraphs into shorter ones before converting.
- Keep links plain so they are easy to spot and click.
Privacy
The converter works entirely in your browser. Your text is not uploaded, logged or shared. Your display preferences (font, size, spacing, theme, fixation) are saved in your browser's local storage so they are there next time, and you can clear them with your browser data. The text itself is never saved.
Frequently asked questions
What is bionic reading?
Bionic reading is a text formatting style that makes the first letters of each word bold, so the eyes land on the bold part and the brain completes the rest of the word. It is meant to guide the eye and keep attention moving through the text.
How do I convert text to bionic reading?
Paste your text into the box. The converted text appears straight away with the first part of every word in bold. Use the fixation slider to bold more or fewer letters, and the other controls to change font, size, spacing and theme.
Does bionic reading actually make you read faster?
The evidence is mixed. Small studies and tests published so far have not found a reliable improvement in reading speed or comprehension for most readers. Some people, including some with ADHD or dyslexia, say it helps them stay focused. Try it and compare, because it is a personal preference.
Is bionic reading good for dyslexia or ADHD?
There is no proof that it treats either condition. Better-supported adjustments for dyslexia include larger text, wider spacing, shorter lines and a clear font, and this tool provides all of those. Use whatever feels comfortable, and talk to a specialist about support.
What does the fixation slider do?
It sets what share of each word is bold. At 50% a six-letter word has three bold letters. Lower values give a subtler look, and higher values make most of the word bold.
What is the Bold every setting?
It lets you bold only every second or third word, which gives your eyes a skipping rhythm, often called the saccade setting. Every word is the standard look.
What are the best settings?
Many people start with 40 to 50% fixation, bold on every word, 18 px type, line height 1.6 to 1.8, a line width around 60 to 70 characters and a sans-serif font. Then adjust one setting at a time.
Can I copy the result into Word, Docs or an email?
Use Copy HTML and paste into an editor that accepts HTML, or Copy Markdown for tools that support double-asterisk bold. You can also download a ready-made HTML page and open it in any browser.
What does the reading ruler do?
It highlights a band the height of one line that follows your mouse or finger, so you can keep your place and block out the lines above and below. Many readers find a line focus helpful.
What is the speed reader tab?
It shows words one at a time (or two or three at a time) at a speed you choose, with a red letter at the optimal recognition point. This method is called rapid serial visual presentation. It is useful for skimming, but comprehension usually drops at high speeds.
What is the Flesch Reading Ease score?
It estimates how easy English text is to read from the average sentence length and the average number of syllables per word. Scores run from 0 (very hard) to 100 (very easy); 60 to 70 is plain English. The tool also shows the Flesch-Kincaid grade level.
Does it work in other languages?
Yes for bolding: it works on any language that uses letters, including accented letters. The readability scores and syllable counts are designed for English and will be less accurate for other languages.
Can I download the converted text?
Yes. Download HTML page saves a self-contained page with your font, size, spacing and theme. You can also copy HTML or Markdown, or print the converted text to a PDF.
Why does my text look different when pasted elsewhere?
Plain text has no bold. The bold marks are HTML or Markdown, so paste into a place that understands one of them. If you paste plain text into a basic text field, you will lose the formatting.
Is Bionic Reading a trademark?
Yes. Bionic Reading is a registered trademark of Bionic Reading AG. This tool is independent and not affiliated with that company. It uses its own simple bolding method and does not copy any proprietary algorithm.
Is my text private?
Yes. Everything happens in your browser. The text is not uploaded or stored. Only your display settings are remembered, in your browser's local storage.
What can I print or save?
Print / save as PDF, CSV and Copy summary work for the tab you are viewing: the bionic text, the speed reader settings or the readability report.
Sources and further reading
- W3C Web Accessibility Initiative, Making Content Usable for People with Cognitive and Learning Disabilities, for guidance on text spacing, line length and readability.
- WCAG 2.2, Success Criterion 1.4.12 Text Spacing and 1.4.8 Visual Presentation, for recommended line height and spacing.
- Flesch, R. (1948), A new readability yardstick, and Kincaid et al. (1975), for the Flesch Reading Ease and Flesch-Kincaid formulas.
- British Dyslexia Association, Dyslexia Style Guide, for font, spacing and layout recommendations.
Sources were consulted in October 2026. Standards and rules can change, so always check the official page for your situation.