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About this tool
Adds optional visual emphasis to the start of each word.
This bionic reading converter emboldens the opening letters of every word to create artificial fixation points, bolding the first ceil(word length × fixation ratio) letters — 50 percent of each word at the standard level 3 — while always leaving at least one letter plain so the contrast survives. It reports exactly what share of the text ends up in bold and outputs both HTML and Markdown. It is for readers who find heavy paragraphs hard to track, and for writers preparing accessible reading copy.
Open Bionic Reading Converter on AltFTool — it loads instantly in your browser.
Paste into the Text to convert box and set the Fixation strength (five levels covering 30-70% of each word) plus the contrast of the unbolded remainder.
The converter bolds the first ceil(word length × ratio) letters of every word, always leaving at least one letter plain.
Check the Letters emphasised percentage and the live Preview, then use Copy HTML or Copy Markdown to export the result.
Five strengths from 30 to 70 percent of each word, plus a contrast control for the remainder.
Shows words, letters, letters bolded and the exact percentage, so the effect is measurable, not vague.
Angle brackets and ampersands in your text are escaped, so the HTML you copy is safe to paste anywhere.
The published evidence says no. Hughes and colleagues in 2023 and an earlier 2022 replication both found no speed or comprehension advantage over ordinary text. Readers who prefer it usually report it helps them hold their place on the line, which is a preference rather than a measured effect.
The first ceil(length × ratio) letters, where the ratio is 0.3 at level 1 up to 0.7 at level 5, with 0.5 as the standard. A seven-letter word at level 3 gets four bold letters, and words of two letters or more always keep at least one plain letter.
Yes. The HTML output uses plain <b> tags and an optional inline opacity on the tail, with your text HTML-escaped, so it pastes into a CMS or an email template without pulling in a script or a webfont.
Word count divided by 238 words per minute, the mean adult silent reading rate for English non-fiction from Brysbaert's 2019 meta-analysis of 190 studies. Technical material runs slower and light fiction faster, so treat it as a rough guide.
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