Readability Checker — Flesch Score & Reading Level

The Flesch Reading Ease score ranges from 0 to 100, where higher numbers indicate easier reading. Scores of 90–100 are considered very easy — typical of comic books and children's literature. Scores of 60–70 are the standard for plain English — most web content, newspapers, and popular magazines fall here. Scores of 30–50 indicate difficult content suitable for college-educated readers. Scores below 30 are very difficult, typical of academic journals and legal documents. The formula calculates score based on average sentence length and average syllables per word — long sentences and polysyllabic words lower the score.

The Flesch-Kincaid Grade Level formula converts the same text metrics into a US school grade level. A score of 8 means an 8th grader (approximately 13–14 years old) can understand the text. Most content guidelines recommend targeting grade 6–8 for general web content and marketing copy. Technical documentation aimed at professionals can comfortably target grade 10–12. Academic research papers often score grade 14–18 (postgraduate level). Grade level should be matched to your audience — writing above their level causes comprehension failures, while writing far below it can seem condescending.

Blog posts and news articles targeting a general audience should aim for a Flesch Reading Ease of 60–70 (grade 7–8). Marketing landing pages and product descriptions benefit from scores of 65–75 — accessible, engaging, and quick to read. Healthcare content for patients should target 70+ (grade 6 or below) because research shows health literacy in the general population is lower than expected. Legal and financial content for professionals can tolerate scores of 40–55 given the subject matter complexity, but plain-language versions for consumers should target 60+.

Average sentence length is one of the two primary inputs to Flesch formulas. The recommended target for web content is 15–20 words per sentence. Sentences over 30 words almost always benefit from being split into two. Active voice produces shorter, more direct sentences than passive voice — "The team completed the project" (5 words) vs. "The project was completed by the team" (7 words). Scan your text for sentences starting with "There is," "There are," "It is," or "It was" — these constructions are usually passive and can be rewritten in active voice with fewer words.

The second primary input to readability formulas is syllable count per word. Replace polysyllabic vocabulary with simpler equivalents where meaning is not lost: "utilize" → "use," "demonstrate" → "show," "subsequently" → "then," "approximately" → "about." Paragraph length also affects perceived readability even if it is not in the formula — paragraphs of 3–5 sentences are easier to read than walls of text. Online readers scan rather than read linearly, so short paragraphs with one idea each match how people actually consume web content.

White space — the empty areas around text elements — significantly affects perceived readability regardless of sentence structure. Generous line height (1.5–1.8 for body text), adequate margins, and spacing between paragraphs reduce visual density and lower cognitive load. Break long sections with subheadings every 200–300 words so readers can navigate and scan. Use bullet lists for three or more parallel items instead of run-on sentences. These visual improvements make content feel more readable even before a single word is changed — they are especially important for mobile readers where screen real estate is limited.