Readability Score Calculator
Paste your text above to get a Flesch Reading Ease score and Flesch-Kincaid Grade Level, along with sentence count, word count, syllable count, and complex word count. Find out what education level your writing actually requires. Nothing is uploaded.
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What the Flesch-Kincaid tests measure
The Flesch-Kincaid formulas are the most widely used readability measures in English, originally developed for the US Navy in 1975 to evaluate whether technical training manuals were written at a level sailors could actually understand. Rudolf Flesch had introduced the underlying Reading Ease formula decades earlier, in 1948. Both formulas rely on the same two inputs: average sentence length and average syllables per word. Longer sentences and longer words both push the difficulty score up.
Flesch Reading Ease runs on a 0 to 100 scale. Higher is easier to read. The exact formula is 206.835 minus 1.015 times the average sentence length, minus 84.6 times the average syllables per word. A score of 90 to 100 is easily understood by an average 5th grader. A score of 60 to 70 is considered plain English, understandable by 13 to 15 year olds. A score below 30 is best understood by university graduates.
Flesch-Kincaid Grade Level translates the same underlying metrics into a U.S. school grade. The formula is 0.39 times average sentence length, plus 11.8 times average syllables per word, minus 15.59. A grade level of 8.4 means an eighth grader would be expected to understand the text on a first read.
Reading the six stats
Sentences, Words, and Syllables are the raw counts the formulas are built from. Words / Sentence and Syllables / Word are the two averages that drive both scores directly. These two numbers explain almost everything about why a score came out the way it did: a high words-per-sentence average means your sentences are running long, and a high syllables-per-word average means your vocabulary is complex.
Complex Words counts words with three or more syllables, since these are the words with the heaviest influence on the score. A text with a high complex word count relative to its total word count will score as harder to read even if the sentences themselves are short. Checking which specific words are landing in that count is the fastest way to find easy wins during a revision pass.
Target scores by content type
General consumer blogs and SEO articles perform best around a Reading Ease score of 60 to 70 and a Grade Level of 7 to 9. This range covers the broadest possible audience without requiring the writer to sound condescending or overly simplistic.
Marketing and advertising copy often aims even lower on the grade scale, frequently 5th to 7th grade, since the reader is skimming quickly and has no patience for parsing complex sentence structure. Short, punchy sentences consistently outperform long ones in ad copy testing.
Academic and technical writing intentionally scores higher, often 12th grade and above, since precision and domain-specific terminology matter more than broad accessibility for that particular audience. A high grade level score is not inherently a problem if the target reader is a specialist.
Legal documents and insurance policies frequently score at the most difficult end of the scale, sometimes requiring graduate-level reading ability, which is a well-documented accessibility problem in those fields rather than a stylistic choice.
How to improve your score
The formula responds to exactly two levers: sentence length and word complexity. Breaking a 30-word sentence into two 15-word sentences lowers both the words-per-sentence average and, by extension, both scores. Look for sentences using “and”, “but”, or a semicolon to join two complete thoughts, since these are usually the easiest to split.
Swapping a complex word for a simpler synonym is the second lever. “Utilize” becomes “use”. “Facilitate” becomes “help”. “Approximately” becomes “about”. Each swap removes syllables directly from the calculation. The syllable counter shows a word-by-word breakdown of your text, which makes it easier to spot exactly which words are carrying the most syllable weight before you start editing.
These two levers do not always move the score in ways that improve the actual writing. A sentence broken at an awkward point for the sake of the score can feel choppy. A more precise word replaced by a vaguer, shorter one can lose meaning. The score is a diagnostic to guide revision, not a target to hit at the expense of clarity.
Other readability formulas
Flesch-Kincaid is the most widely used readability formula but not the only one. The Gunning Fog Index estimates years of formal education needed to understand a text and weights complex words heavily. SMOG (Simple Measure of Gobbledygook) is considered particularly accurate for healthcare and patient materials. Coleman-Liau calculates readability from characters per word rather than syllables, which makes it more consistent for text with many short technical terms or abbreviations where syllable counting gets ambiguous. Different formulas can produce different grade level estimates for the same text since each weighs sentence length and word complexity slightly differently. Flesch-Kincaid remains the standard reference point across SEO, journalism, and most style guides.