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Free Readability Checker – Reading Level & Readability Score
Check your text's readability, reading grade level, Flesch score, sentence length distribution, word complexity, and reading time with our free, 100% private readability checker.
What is a Readability Checker?
A readability checker is an analytical tool that calculates how easily a reader can understand and navigate written English. Rather than assessing literary talent or subjective writing style, readability formulas evaluate objective structural characteristics—including average sentence length, syllable depth, polysyllabic word density, and vocabulary familiarity.
By translating linguistic structure into standardized metrics—such as the Flesch Reading Ease score (0–100) or the Flesch-Kincaid Grade Level (Grades 1–12+)—readability checkers help writers, digital editors, healthcare practitioners, educators, and corporate communicators calibrate their writing to their intended audience's comprehension bandwidth.
What is an Ideal Readability Score?
For general consumer websites, blogs, and public communications, an ideal Flesch Reading Ease score is between 60 and 70, corresponding to an 8th-to-9th grade reading level. Texts written in this range can be read effortlessly by approximately 85% of the adult English-speaking population, minimizing cognitive fatigue, reducing bounce rates, and increasing reader retention.
The 8 Major Readability Formulas Explained
ReadabilityPro calculates eight independent mathematical readability algorithms to provide a comprehensive evaluation of text difficulty:
Published by Rudolph Flesch in 1948, this 0–100 scale evaluates average sentence length (ASL) and average syllables per word (ASW). Higher scores indicate easier reading: 90–100 is very easy (5th grade), 60–70 is standard plain English, and scores below 30 denote difficult academic or legal prose.
206.835 - 1.015×(words/sentences) - 84.6×(syllables/words)
Developed in 1975 for the United States Navy by J. Peter Kincaid, this formula converts readability directly into U.S. school grade levels. An 8.2 score indicates that an average 8th-grade student can comprehend the material. Originally calibrated for military technical manuals, it is widely utilized across defense standards, state insurance plain-language statutes, and school curricula.
0.39×(words/sentences) + 11.8×(syllables/words) - 15.59
Created in 1952 by Robert Gunning, the Fog Index measures the formal education years needed to understand writing on a first read. It heavily penalizes polysyllabic words (words with 3+ syllables), making it an exceptional test for eliminating corporate jargon and business buzzwords.
0.4 × [ (words/sentences) + 100×(complex_words/words) ]
Developed by G. Harry McLaughlin in 1969, SMOG (Simple Measure of Gobbledygook) is calibrated for 100% complete comprehension (unlike Flesch-Kincaid's 50% threshold). It is widely recommended in health literacy guidelines by institutions like the National Institutes of Health (NIH) and CDC for assessing patient educational handouts and informed consent forms.
1.0430 × √(30 × complex_words / sentences) + 3.1291
Designed by Meri Coleman and T. L. Liau, this metric calculates grade levels using mechanical letter counts and sentence counts per 100 words rather than syllables. This bypasses pronunciation exceptions, providing reliable, deterministic character-level scoring.
0.0588 × L - 0.296 × S - 15.8
Where L = average letters per 100 words, and S = average sentences per 100 words.
Created in 1967 for the U.S. Air Force, the ARI evaluates character stroke counts per word alongside words per sentence. Widely utilized in technical writing, engineering manuals, and automated documentation generators.
4.71×(characters/words) + 0.5×(words/sentences) - 21.43
Developed by Edgar Dale and Jeanne Chall, this formula compares words against a calibrated lexicon of 3,000 familiar everyday English words. Any word outside the list is flagged as unfamiliar, ensuring accurate assessment of vocabulary difficulty.
0.1579×(unfamiliar% PDW) + 0.0496×(words/sentences) + (PDW > 5% ? 3.6365 : 0)
The +3.6365 constant adjustment applies only when unfamiliar words (PDW) exceed 5% of total words.
Devised by Carl-Hugo Björnsson, LIX is an international language-independent readability standard widely used in Europe. It calculates sentence length and the percentage of words longer than 6 letters.
(words / sentences) + (words > 6 letters × 100 / words)
Flesch Reading Ease Score & Grade Level Conversion Chart
Use this conversion reference to match your Flesch Reading Ease score to school grade levels, reading difficulty, and typical target publications:
| Flesch Score |
Grade Level |
Reading Difficulty |
Typical Publications & Context |
| 90 – 100 |
5th Grade |
Very Easy |
Comics, children's literature, basic consumer notices |
| 80 – 89 |
6th Grade |
Easy |
Popular pulp fiction, consumer advertising, lifestyle blogs |
| 70 – 79 |
7th Grade |
Fairly Easy |
Mass-market web articles, general magazines, SaaS landing pages |
| 60 – 69 |
8th – 9th Grade |
Standard Plain English |
Major newspapers (Time, Newsweek), business memos, civic notices |
| 50 – 59 |
10th – 12th Grade |
Fairly Difficult |
Broadsheet journalism (NY Times, Wall Street Journal), textbooks |
| 30 – 49 |
College (13th–16th) |
Difficult |
Academic journals, technical white papers, engineering specifications |
| 0 – 29 |
College Graduate |
Very Difficult |
Legal briefs, statutory legislation, scientific research papers |
How to Lower the Reading Level of Your Writing
Writing with a lower reading grade level does not mean dumbing down complex thoughts. Linguistic analyses of celebrated works by authors such as Ernest Hemingway, George Orwell, and Cormac McCarthy frequently demonstrate 4th-to-6th grade reading scores because they favored concise Anglo-Saxon vocabulary, short sentences, and active syntax.
- Split sentences over 25 words: Long compound clauses overwhelm human short-term working memory. Divide sentences connecting multiple thoughts with a period.
- Replace multisyllabic Latinate jargon: Swap utilize for use; swap facilitate for help; swap commence for start.
- Eliminate filler words and qualifiers: Remove padding words like really, basically, actually, and very.
- Adopt active voice: Active voice places the subject before the verb, eliminating passive auxiliary constructions and clarifying who is taking action.
- Break text into short 2-to-3 sentence paragraphs: On mobile screens, long paragraphs become intimidating walls of text that cause readers to abandon the page.
Recommended Reading Level Benchmarks by Audience
Selecting the appropriate target reading level depends entirely upon your readership's background, context, and stress level:
Consumer Web & E-Commerce
Target: Grade 6.0 – 7.9 (Flesch 65–75)
Mainstream online shoppers, product landing pages, customer support help centers, and general interest newsletters.
Business & Corporate Communication
Target: Grade 8.0 – 10.0 (Flesch 60–70)
Internal company memos, executive summaries, client proposals, B2B product documentation, and industry case studies.
Healthcare & Patient Information
Target: Grade 5.0 – 6.5 (SMOG ≤ 6.0)
Prescription instructions, patient intake forms, surgical consent documents, and public health advisories.
Technical Software & Engineering
Target: Grade 10.0 – 12.0 (Flesch 50–60)
Developer portals, REST API documentation, system architecture specifications, and engineering white papers.
Frequently Asked Questions About Readability & Scores
What is a readability checker?
A readability checker is an analytical tool that calculates how easy or difficult a text is to read. It analyzes structural factors like sentence length, word count, and syllable complexity against mathematical formulas such as Flesch Reading Ease, Flesch-Kincaid Grade Level, and Gunning Fog.
What is a good Flesch Reading Ease score?
A Flesch Reading Ease score between 60 and 70 is widely recommended by plain language guidelines and content strategy standards for general public writing, websites, and business communications. Scores of 60 to 70 correspond to an 8th-to-9th grade reading level, which approximately 85% of adult English readers can easily comprehend.
What reading level should a website target?
The recommended reading level for general consumer websites, blogs, and landing pages is 7th to 8th grade (Grade 7.0–8.9). This ensures high comprehension, low cognitive fatigue, and improved user engagement across desktop and mobile devices.
Why do famous authors like Ernest Hemingway score at an elementary grade level?
Linguistic analyses of literary works by authors like Ernest Hemingway, George Orwell, and Cormac McCarthy show they frequently scored at a 4th-to-6th grade reading level by choosing concise vocabulary, short sentences, and active verbs. A lower grade level does not mean childish writing; it signifies precision, emotional power, and the elimination of superfluous fluff.
Is ReadabilityPro completely free and private?
Yes. ReadabilityPro is 100% free with no registration or paywalls. Your text never leaves your browser—all linguistic analysis is executed locally inside your web browser with zero server storage. Advertisements displayed on the site may use cookies for ad delivery; see our Privacy Policy.
100% Client-Side Privacy Guarantee
All text calculations on ReadabilityPro run entirely in your web browser using client-side JavaScript. Your text, drafts, manuscripts, patient records, and proprietary legal documents are never uploaded to any remote server or stored in a database.
