Sentence Rhythm Analyzer

In short Readability formulas count syllables and sentence length and produce a grade level, which is why they rate a page of identically-shaped 15-word sentences as perfectly readable when it is exhausting to read. What actually makes prose readable is VARIATION — long sentences followed by short ones, the rhythm changing enough that attention keeps being renewed. This measures that directly. A variation score above 0.5 generally reads well; below 0.35 the prose sounds mechanical, and four or more similar-length sentences in a row is where attention reliably drifts. The fix is not to rewrite everything but to break the runs. Find the longest stretch of same-length sentences and split one, or join two, and the whole passage loosens — a single very short sentence after three long ones does more for a paragraph than any amount of word-level editing. It is also the fastest way to spot text that was generated rather than written, because generated prose tends towards a uniform sentence length. The measure works on any language that marks sentence boundaries with full stops, though the thresholds were calibrated on English and languages with very different sentence conventions will need them read more loosely.