Free Readability Checker
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 abstract, paper or lay summary live while you edit, and download a PDF report to share with co-authors.
Trusted by researchers publishing in
How to check readability in three steps
Paste your text
An abstract, an introduction, a lay summary or a full chapter. All six scores compute instantly.
Read the consensus
The average grade level is your headline number; the individual formulas show how sentence length and word length each contribute.
Revise, then export
Watch the scores move as you edit, and download the PDF report when the text lands in your target band.
A readability checker built for research 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.
Research-calibrated targets
Interpretation bands for papers (14-16+), lay summaries (8-12) and participant documents (6-8), not generic blog-writing advice.
PDF report included
Export every score, the reference bands and your text as a dated report, generated by ProofreaderPro AI, ready for co-authors.
Diagnostics, not just scores
Average sentence length, syllables per word and complex-word share show exactly which lever to pull.
Why readability matters in academic publishing
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 academic 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 skim before they read, and an abstract they can absorb in one pass frames the whole review. Interdisciplinary readers, ESL colleagues and journalists decide from the same abstract whether your work travels beyond your subfield. And the documents around the paper 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. For sentence-level techniques, see our guide on writing a research abstract that gets read.
The six readability formulas, explained for researchers
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, economics abstracts near 10, 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. It answers the same question as Flesch-Kincaid through a different lens: when the two agree, 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 methods 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 are scored live by 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
Researchers and PhD students
Check abstracts, introductions and response letters before submission, and keep discussion sections out of grade-20 territory.
Health and clinical researchers
Score patient information sheets and consent forms against the grade 6-8 expectations of ethics boards, using SMOG.
Grant writers
Bring lay summaries and project descriptions into the plain-language range funders increasingly require.
Students and ESL writers
See how sentence structure drives difficulty, and learn to write clearly without simplifying the ideas.
Readability checker FAQs
What is a good readability score for a research paper?
Why does my Flesch Reading Ease score show 0?
Do journals or institutions require readability scores?
How do I lower my grade level without dumbing the science down?
Scoring grade 19? Let the editor tighten it.
ProofreaderPro shortens overloaded sentences and trims padding with tracked changes, so your paper reads at the level your reviewers expect without losing a single claim.
Improve my readability free