AI Readability Score

What this tool calculates

This tool runs five classic, rule-based readability formulas on your text: Flesch Reading Ease (0-100, higher is easier), Flesch-Kincaid Grade Level, Gunning Fog Index, Coleman-Liau Index, and the Automated Readability Index. Each formula combines sentence length, word length, and syllable counts (estimated with a vowel-cluster heuristic, not a dictionary) into a single number that approximates the US school grade level needed to comprehend the text.

Despite the name, none of these formulas involve a language model — they're the same deterministic equations that have been used in publishing and education since the 1970s. "AI" readability here refers to a common use case: checking whether content written by or for an AI system (chatbot responses, generated articles) reads at an appropriate level, not that the scoring itself uses AI.

When to use it

Use it to check whether marketing copy, documentation, or support articles match your target audience's reading level — general consumer content usually aims for 60-70 Flesch Ease (8th-9th grade), while technical documentation can reasonably sit lower. It's also useful for auditing AI-generated content before publishing: LLM output often defaults to longer, more complex sentences than house style calls for, and a quick score flags pages that need simplifying.

Because five formulas run at once, look for agreement rather than trusting a single number — if Flesch-Kincaid says 8th grade but Gunning Fog says college level, the discrepancy usually means the text has a mix of short simple sentences and a few very long, jargon-heavy ones dragging the average.

Example

Paste "The rate limiter uses a token bucket algorithm to smooth bursty traffic while enforcing an average request rate." and expect a Flesch Ease in the 30s-40s (Difficult/College level) — driven by long words like "algorithm" and "enforcing" and a single dense sentence. Splitting it into two shorter sentences and swapping "utilizes" for "uses" (already done here) typically raises the score by 10-20 points.