Readability Score Checker
Paste any text to see its reading grade level across five formulas: Flesch-Kincaid, Gunning Fog, SMOG, Flesch Reading Ease, and ARI. See who can read your content.
How to Check Your Text's Readability
Features
The Five Readability Formulas Compared
Flesch-Kincaid Grade Level (1975) is the gold standard in US education and government. It outputs directly in US grade levels (Grade 8 = 8th-grade reading ability). The formula weights words per sentence and syllables per word equally. Used by the US Department of Defense for technical manuals.
Gunning Fog Index (1952) was designed for the newspaper and business writing industry. It counts "complex words" (3+ syllables) as a separate input to the formula, making it more sensitive to technical jargon. A Fog score of 12 means 12 years of schooling is needed. SMOG Index (1969) was developed specifically for healthcare patient education materials and is required by many health literacy guidelines. It has the best track record for predicting comprehension in non-expert populations.
Flesch Reading Ease is the inverse of Flesch-Kincaid on a 0–100 scale rather than a grade number — useful when you want a single "easier is higher" number rather than a grade to interpret. Automated Readability Index (ARI) is the odd one out: instead of counting syllables, it counts characters per word, which makes it faster to compute and slightly more consistent across text with unusual or technical vocabulary where syllable counting tends to go wrong.
Where the Five Scores Disagree With Reality
All five formulas measure the same two things at bottom — sentence length and word length — and that's both their strength and their ceiling. None of them read for meaning. A sentence can be short and choppy without being any easier to actually follow, and a formula will still reward it. A word can be long but completely familiar ("understanding", "beautiful") while a short word can be genuinely obscure jargon the formula has no way to flag. Research comparing Flesch-Kincaid grade predictions against independently-rated text difficulty has found it correctly classifies well under half of texts by grade level — useful as a directional signal, not a precise measurement.
None of the five formulas account for the reader's prior knowledge either, which matters more than sentence structure for a lot of real content. A physics paper full of short, grammatically simple sentences about quantum entanglement will still score as difficult to a non-physicist, because the difficulty lives in the concepts, not the syntax — and no surface-level formula can see that. Treat the grade level here as one input alongside your own judgement about your actual audience, not a target to hit for its own sake.
That's also why the tool shows all five scores side by side rather than picking one as authoritative — when Flesch-Kincaid, Gunning Fog, and SMOG land within a grade or two of each other, that agreement is a stronger signal than any single number. When they diverge sharply, it's usually because the text has an unusual mix of short sentences and long, jargon-heavy words — worth a second look either way.
Readability for Web Content, SEO, and Marketing
Google has confirmed that user engagement signals influence ranking, and readability affects engagement. A study by Backlinko found that content ranked at the top of Google results is written at an average Grade 9 reading level — accessible but not dumbed down. For broad audience content, the Hemingway App popularised the idea of writing at Grade 5–7 for maximum accessibility, while still maintaining authority.
For email marketing, readability at Grade 6–8 significantly improves open-to-read conversion. HubSpot research found that marketing emails written at the Grade 6 reading level have 25% higher click-through rates than emails at the Grade 10+ level. After checking your score, use the Word Frequency Counter to identify overused complex words that inflate the reading grade, and consider replacing them with simpler synonyms using Find & Replace.
Lowering the Grade Without Flattening the Writing
The fastest way to drop a grade level is also the laziest: chop every sentence in half. It works on the formula and often makes the writing worse — a string of short, disconnected sentences reads choppier, not clearer. A better first move is finding the one or two long sentences doing three jobs at once and splitting only those, while leaving sentences that are already doing one job cleanly alone.
Vocabulary swaps matter more than sentence length for most business and web writing. "Utilise" costs a syllable that "use" doesn't, "facilitate" costs two that "help" doesn't, and neither swap changes the meaning. Nominalisations are the other quiet inflator — "we made a decision" scores worse than "we decided" despite saying exactly the same thing, because the formula counts the extra syllables in "decision" and the extra word in "made a". Neither fix requires dumbing down an argument, only trimming the padding around it.
A concrete before-and-after: "The implementation of the aforementioned strategy necessitates the utilisation of additional resources" scores at roughly Grade 18 — postgraduate level — for a sentence that just means "doing this needs more resources." Rewritten as "This strategy needs more resources," the same sentence drops to Grade 4. Nothing about the underlying point changed; only the padding around it did. Run both versions through the tool above and the gap is obvious immediately, which is usually the fastest way to see the effect of a rewrite than reading either version in isolation.
Who Needs Readability Scores
Content writers and bloggers use readability scores to ensure their articles are accessible to their target audience. A cooking blog serving home cooks should write at Grade 7–8; a medical journal article targeting physicians can justify Grade 14–16.
Government and legal writers are often required by plain language legislation to produce documents at specific reading levels. The UK government Plain English Campaign and the US Plain Writing Act both reference Flesch Reading Ease targets. Legal documents written for consumers must be comprehensible, not just legally accurate.
Healthcare communicators writing patient education materials typically target a Grade 6–8 reading level (SMOG score ≤ 10) because research shows this maximises patient comprehension and compliance across socioeconomic groups, regardless of the patient's actual education level. The Word Counter helps you keep track of document length alongside the readability check.
UX writers and product teams check onboarding flows, error messages, and help docs against a grade level target because a confused user at a Grade 12 tooltip is a support ticket waiting to happen. ESL and language learners use the grade level as a rough proxy for how approachable a piece of writing will be before committing time to reading it in full — not a perfect substitute for a CEFR rating, but a fast first filter.