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About this tool
Measure your text's Flesch-Kincaid grade and build a rewrite prompt targeting a specific grade or reading level.
The Reading Level Prompt Adjuster scores any text with the Flesch-Kincaid grade formula (0.39 × words-per-sentence + 11.8 × syllables-per-word − 15.59) and builds an AI rewrite prompt targeting the grade band you choose, from grades 2-3 to college level. Instead of vaguely asking an AI to "simplify this", the generated prompt sets checkable rules: a maximum sentence length, plain-word substitutions and a ban on adding or changing content. Teachers, technical writers and accessibility editors get rewrites they can verify by re-scoring.
Open Reading Level Prompt Adjuster on AltFTool — it loads instantly in your browser.
Add your input to the workspace.
Adjust the options until the result looks right.
Copy or download the output and put it to work.
Your text's actual Flesch-Kincaid grade, words per sentence and syllables per word are computed locally and embedded in the prompt.
Each grade band sets a concrete maximum sentence length derived from the FK formula, not just "make it simpler".
The prompt forbids adding, removing or reordering content — only the language changes, with technical terms optionally kept and defined.
It is a readability score that estimates the US school grade needed to understand a text, computed as 0.39 × (words per sentence) + 11.8 × (syllables per word) − 15.59 (Kincaid et al., 1975). A score of 8.0 means an average eighth-grader can read the text; this tool computes it locally in your browser.
Plain-language guidance for public-facing writing commonly targets grades 6-8. Average adult reading comfort sits well below college level, so unless your audience is specialist, the grades 6-8 band is the safest default this tool offers.
It uses the standard heuristic of counting vowel groups with silent-e handling, which is what most automated readability tools do. Scores are typically within about one grade of dictionary-based counts; for borderline cases, judge by the words-per-sentence figure too, which is exact.
The Flesch-Kincaid formula averages over sentences and words, so on very short samples one unusual word can swing the grade by several levels. The tool refuses to score fewer than 10 words rather than give a misleading number.