Readability Scores: What They Actually Measure and When to Care About Them

Flesch-Kincaid produces two related metrics. The Flesch Reading Ease score (0-100) estimates how easy text is to read: 0-30 is very difficult (academic/professional), 60-70 is 'standard' (8th-9th grade), 90-100 is very easy (simple, conversational). The Flesch-Kincaid Grade Level converts this to a U.S. education grade level. Both are calculated from average sentence length and average syllable count per word. A lower grade level and higher reading ease score means shorter sentences and simpler words. These metrics were originally developed for evaluating military documentation readability in 1948.

For most web content, a Flesch Reading Ease score above 60 (grade level 8 or lower) is a common target. The AP Stylebook and many journalism schools teach writing to a 6th-8th grade reading level for general audiences. For technical documentation: grade level 10-12 is appropriate. For legal or medical writing: higher grade levels may be unavoidable but shouldn't be striven for. For marketing copy and email: aim for reading ease 70+. That said, these are guidelines, not rules — the right score depends on your specific audience. Academic writing for PhD readers appropriately has a grade level of 16+.

Yes, but it's the lowest-effort approach and has diminishing returns. Readability scores improve when you use shorter sentences and shorter words. Breaking 'In consideration of the aforementioned circumstances' into two sentences improves the score but doesn't actually make 'aforementioned' easier to understand. The higher-leverage changes are choosing plain words (use 'because' instead of 'in light of the fact that'), using active voice, giving examples for abstract concepts, and structuring information logically so the reader isn't holding too much in working memory. Scores can be gamed — they measure sentence and word length, not actual comprehension.