Bionic-Style Reading Converter (Bold First Letters)

This converter bolds the first part of every word, the look made popular by the Bionic Reading® method, whose idea is that your eyes skim the bold starts and your brain fills in the rest. You get it as Unicode bold letters that paste into social posts and chats, as HTML with <b> tags for a web page, or as Markdown. Choose how much of each word is bold and whether every word or only every second, third or fourth word is marked.

How to use this tool

1. Paste your text.
2. Pick the output: Unicode bold for anywhere you can paste text, HTML for web pages, or Markdown for notes and documents.
3. Set the share of each word in bold (50% is a common choice) and how often words are marked.
4. Copy the converted text.

Formula

Bold letters = ceil(word length × share), at least 1, and always at least one normal letter for words longer than one letter; words of 1–3 letters get 1 bold letter

Words are counted in user-perceived characters, so accented letters and emoji are not split. Unicode bold uses the Mathematical Alphanumeric Symbols block (sans-serif bold from U+1D5D4, serif bold from U+1D400), which only covers A–Z, a–z and 0–9; accents stay attached, and letters in other alphabets keep their normal form in that mode. HTML output escapes &, < and >. Bionic Reading® is a registered trademark of Bionic Reading AG; this free tool imitates the visual style and is not affiliated with the company or its app.

Example

With 50% bold, “Reading is fun” becomes Reading is fun in Markdown: Reading has 7 letters, and half of 7 rounded up is 4. In HTML, “Hello world” becomes <b>Hel</b>lo <b>wor</b>ld, because 5 × 0.5 rounds up to 3.