CodeKitHubWhat Is This Tool?
Bionic Reading is a text-formatting technique that bolds the first 30-50% of letters in each word. The idea, popularized by the Bionic Reading app and adopted by several e-readers and browser extensions, is that a reader's brain already predicts the rest of a word from its first letters — bolding that fixation point creates a visual anchor that can reduce how long the eye needs to linger on each word.
This tool applies the same rule client-side: for every word, it bolds round(length × ratio) letters (at least one) and leaves the rest normal weight, then lets you copy the result as HTML with real <strong> tags you can paste into an editor, email, or web page.
Why Use It?
- Three intensity presets (light/medium/strong) so you can match the effect to your own reading style or the density of the text.
- Live preview updates as you type — no need to click a separate "convert" button.
- Copy as real HTML (<strong> tags), ready to paste into a blog post, note-taking app, or email that supports rich text.
- Runs entirely in your browser — nothing you paste is sent anywhere.
- Free, no account, no length limit.
How to Use
- Paste or type your text into the input box.
- Choose a bold intensity — light, medium or strong.
- Watch the live preview below update automatically.
- Click "Copy as HTML" to copy the formatted result, including the <strong> tags.
Example
Input
Bionic Reading bolds the first part of each wordOutput
𝐁ionic 𝐑eading 𝐛olds the 𝐟irst 𝐩art of 𝐞ach 𝐰ord (rendered as bold text, not literal bold Unicode characters)The actual output uses real HTML <strong> tags, not Unicode bold characters — so it stays selectable, searchable and accessible, unlike some other "bold text" tools.
Frequently Asked Questions
Is Bionic Reading scientifically proven to increase reading speed?
Evidence is mixed. Some readers report it genuinely helps them focus and skim faster, especially for dense or unfamiliar text; controlled studies on reading speed and comprehension haven't found a consistent, large effect for everyone, and some readers find it distracting rather than helpful. It's worth trying on your own material to see whether it works for you personally, rather than assuming it will.
How much of each word gets bolded?
A fixed percentage of each word's letter count, rounded to the nearest whole letter, with a minimum of one bolded letter even for very short words. "Light" bolds about 30% of each word, "Medium" about 40%, and "Strong" about 50% — longer words get proportionally more bolded letters than short ones.
Can I paste the result into Word, Notion or an email?
Yes — "Copy as HTML" copies real <strong> tags. Apps that accept pasted HTML (most rich-text editors, many email clients, Notion, WordPress) will render the bold formatting directly. Plain-text-only destinations (like a code editor or a plain textarea) will instead show the literal HTML tags, since they don't render markup.
Does this work for languages other than English?
It bolds any run of Latin-alphabet letters, including accented characters (é, ñ, ü, etc.), so it works reasonably well for most Western European languages. It does not currently handle non-Latin scripts (Chinese, Arabic, Cyrillic, etc.) — Bionic Reading's "bold the start of the word" concept doesn't map cleanly onto scripts without the same word-recognition mechanics anyway.