Paste any text and see it converted to bionic reading instantly. Bolds the fixation point of each word, adjustable intensity, free, no signup.
Intensity
How much of each word gets bolded
Copies as rich text (bold preserved) into most apps, or as **markdown** where rich text isn't supported.
Bionic reading bolds the first part of each word, an artificial fixation point, on the idea that your brain can recognize the bolded fragment and fill in the rest of the word with less conscious effort. The technique was popularized by Swiss typographer and developer Renato Casutt in 2022 and spread quickly on Reddit and TikTok as a visual trick for reading dense text on a screen.
This tool applies the same idea to any text you paste in, with a control over how much of each word gets bolded. It does not require an account, a browser extension, or any signup.
For the full story, including where the technique came from, how it compares to other reading methods, and a closer look at the research, see the complete guide to bionic reading.
For most words, the converter bolds a fixation prefix, roughly the first 30 to 50 percent of the word's letters depending on your chosen intensity, and leaves the rest unbolded. Short words of one to three letters just get their first letter bolded, since bolding most or all of a three-letter word would defeat the point of a partial fixation cue. Numbers and punctuation pass through untouched.
The intensity control changes that prefix ratio: Low bolds about 30 percent of each longer word, Medium (the default) bolds about 40 percent, and High bolds about 50 percent. There is no single correct setting; it comes down to what feels easiest to scan for your own eyes and the material you are reading.
Be careful with the marketing claims here. Controlled research, including a 2025 eye-tracking study, has not found a reliable reading-speed improvement from bionic-style bolding, and some earlier informal testing found no comprehension gain either. This is a case where the viral popularity of a technique has outrun the evidence for it.
What does show up consistently, mostly in anecdotal reports rather than controlled studies, is that some readers say the bolded fixation points help them stay locked onto the line and reduce skipping around the page. This comes up especially often among readers with ADHD, who report an easier time maintaining focus on dense text, even without a measured speed or comprehension boost. If that description sounds like you, it is worth trying on your own material rather than assuming it will or won't work based on the general research.
Bionic reading and RSVP (rapid serial visual presentation) both get grouped under "speed reading tricks," but they work in completely different ways. Bionic reading is a static formatting change: it bolds part of each word on the page and leaves the rest of the reading process, eye movement, pacing, everything, up to you. RSVP removes eye movement from the equation entirely by flashing one word at a time at a fixed point on screen, at a speed you control.
| Technique | How it works | Evidence for speed gain | Try it |
|---|---|---|---|
| Bionic reading | Bolds a fixation prefix on each word; you still scan the page yourself | Weak; controlled studies show no reliable speed gain | This converter, above |
| RSVP | Flashes one word at a time at a fixed optimal recognition point, at a set WPM | Removes eye movement; speed is directly adjustable and measurable | Try the RSVP demo |
Curious which one suits you? Open the full RSVP reader and compare it directly against the bionic conversion above.
Bionic reading is a text formatting technique that bolds the first part of each word, usually 30 to 50 percent of its letters, to create an artificial fixation point. The idea, popularized by Swiss typographer Renato Casutt in 2022, is that your eyes and brain can recognize a bolded word fragment and complete the rest of the word automatically, guiding your eyes through a sentence with less effort.
The evidence is mixed and the claims are often overstated. A 2025 eye-tracking study found no reliable improvement in reading speed from bionic-style bolding, and some earlier informal testing groups reported no comprehension gain either. What is more consistently reported, mostly anecdotally rather than in controlled studies, is that some readers, including a number of readers with ADHD, say the bolded fixation points help them stay focused on the line and resist skipping around the page. Treat it as a focus aid some people find helpful, not a proven speed-reading method.
No. "Bionic Reading" is a trademark of Renato Casutt, and this converter is an independent tool inspired by the general bolded-fixation technique. It is not affiliated with, endorsed by, or connected to the official Bionic Reading brand, its website, or its browser extension.
Yes. The copy button copies rich text with real bold formatting, which pastes with the bolding intact into apps that support rich text, such as Google Docs, Notion, or an email client. If an app only accepts plain text, the tool falls back to **markdown-style** bold markers so you still get a usable result.
Yes, completely free with no signup, no account, and no limit on how much text you convert. Everything runs in your browser, so your pasted text is never uploaded or stored anywhere.
"Bionic Reading" is a trademark of Renato Casutt. This is an independent converter tool inspired by the general bolded-fixation technique and is not affiliated with or endorsed by the official Bionic Reading brand.
Try the free RSVP reader next, up to 400 WPM, no signup, and see the difference between a formatting trick and a measurable speed method.
Open the RSVP Reader