Free Readability Checker Six Formulas, One Honest Score
Score your writing with the six standard readability formulas at once: Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog, SMOG, Coleman-Liau and ARI. See the grade level of your essay, abstract or article, with targets calibrated for real documents rather than generic blog advice. Unedited AI text tends to land in one narrow difficulty band; knowing your numbers is the first step to writing that actually fits its reader.
Scores your text with six readability formulas at once: Flesch, Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau and ARI.
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How to check readability in three steps
Paste your text
An abstract, an essay, an introduction or a lay summary, up to 1,000 words per pass. All six scores compute in one run.
Read the consensus
The average grade level is your headline number; the individual formulas show how sentence length and word length each contribute.
Revise toward your band
Split the longest sentences, swap nominalisations for verbs, then run the scores again until the text lands in your target band.
A readability checker built for serious writing
Six formulas, one view
Flesch, Flesch-Kincaid, Fog, SMOG, Coleman-Liau and ARI side by side, so one quirky formula never misleads a revision.
Calibrated targets
Interpretation bands for research papers (14-16), lay summaries (8-12) and participant documents (6-8), not one-size-fits-all advice.
Diagnostics, not just scores
Average sentence length, syllables per word and complex-word share show exactly which lever to pull.
Private by design
All six formulas compute on your own device. Your draft never leaves the browser, which matters for unpublished work.
Why readability scores matter, from classrooms to journals
Readability formulas estimate how much education a reader needs to follow a text on first reading. They cannot judge logic or evidence, but they are remarkably good at flagging the two habits that make prose exhausting: very long sentences and unbroken runs of long words. Analyses of published research put typical journal articles around grade 14 to 16 and medical abstracts near 18, and large-scale studies show scientific writing has been getting steadily harder to read for decades. Editors, funders and ethics boards now push in the opposite direction.
The practical stakes are concrete. Reviewers and markers skim before they read, and an abstract they can absorb in one pass frames everything that follows. Interdisciplinary readers, ESL colleagues and journalists decide from the same abstract whether your work travels beyond your subfield. And the documents around a project are formally gated: consent forms at grade 6 to 8, lay summaries in plain language, press releases readable by anyone. One manuscript routinely needs three different readability bands, which is why this checker reports them all.
AI drafting adds its own wrinkle. Ask a chatbot for an essay and the output usually sits in one narrow difficulty band from first sentence to last: consistently mid-length sentences, consistently moderate vocabulary. Human writing drifts, simplifying where the reader needs a breather and condensing where the argument earns it. Checking your scores section by section, rather than once for the whole document, is a quick way to find stretches that were never revised. Pair this page with the burstiness checker for rhythm and the TextPulse humanizer when a draft needs the rewrite, not just the diagnosis.
The six readability formulas, explained
Each formula was built for a different audience, which is exactly why checking all six beats trusting any one of them.
Flesch Reading Ease
1948The oldest and most widely reported score. Combines average sentence length with syllables per word on a 0-100 scale where higher means easier. Published research typically scores below 30; an abstract reaching 30-50 stands out for clarity.
Flesch-Kincaid Grade
1975The US Navy's reformulation of Flesch that reports a school grade, which made it the default benchmark in readability research. Journal analyses place medical abstracts near grade 18 and discussion sections around 16.
Gunning Fog Index
1952Pairs sentence length with the share of words of three or more syllables, making it the most jargon-sensitive formula. If Fog sits well above your Flesch-Kincaid grade, dense vocabulary rather than sentence length is the problem.
SMOG Index
1969Counts polysyllabic words across 30 sentences and predicts full comprehension rather than partial understanding. The standard in healthcare: consent forms and patient information sheets are typically required at grade 6-8, measured with SMOG.
Coleman-Liau Index
1975Uses characters per word instead of syllables so machines can score text reliably. When it agrees with Flesch-Kincaid, trust the number; when they diverge, your words are unusually long or short for the sentence structure.
Automated Readability Index
1967Built for military technical manuals from characters per word and words per sentence. Because it was designed for procedural writing, it responds strongly to long sentences, making it a good early warning for sections that chain steps into 50-word constructions.
Which grade level should you aim for?
Match the score to the document, not the other way around. The same project usually needs all three of the first bands.
The same finding, eighteen grades apart
Both passages score live in this tool. Nothing was simplified except the sentences.
"The implementation of the proposed methodological framework necessitates a comprehensive consideration of the multifaceted institutional factors that have the potential to significantly influence the successful operationalization of community-based interventions across heterogeneous demographic contexts."
One 33-word sentence, five nominalisations, fourteen complex words.
"Implementing the framework requires attention to local institutions. Their influence on community programs is large, and it differs across demographic settings. Any rollout plan should account for these differences."
Three sentences, verbs instead of nominalisations, every claim intact.
Who uses the readability checker
Students
Check essays and assignments against the band your reader expects, and learn how sentence structure drives difficulty.
Researchers and academics
Keep abstracts, introductions and discussion sections out of grade-20 territory before reviewers see them.
Health and grant writers
Score consent forms against the grade 6-8 expectations of ethics boards, and bring lay summaries into plain-language range.
Marketing and SEO teams
Web readers bounce off grade-16 paragraphs. Keep articles and landing pages in the band general audiences actually finish.
Scoring grade 19?
TextPulse tightens the whole draft.
The humanizer shortens overloaded sentences, varies flat rhythm and trims AI-flavoured padding with a tracked-changes view of every edit, so your writing reads at the level your audience expects without losing a single claim.