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Flesch-Kincaid calculator
Paste your text for the Flesch Reading Ease score and the Flesch-Kincaid grade level, plus word, sentence, and syllable counts and your longest sentences. It runs entirely in your browser. Free, no signup.
Runs in your browser. Your text is never uploaded or stored.
College — some effort required
Longest sentences
Sentence length is the input you can most easily change. Splitting these does more for readability than swapping individual words.
- Each topic is tagged, conditioned, and assembled at publish time, which lets one set of source files produce a web help site, a printed PDF, and a Markdown feed for an AI assistant without rewriting anything.(36 words)
- Structured authoring separates content from its presentation so a single source can publish to many outputs.(16 words)
- Writers create small, reusable topics instead of long documents.(9 words)
On the syllable count: Syllable counts use a vowel-group heuristic, not a pronunciation dictionary, so they are approximate. On ordinary English prose the count is within roughly 2 to 5 percent of the true total; unusual words, names, and acronyms are where it drifts most. That moves the grade level by a few tenths at most.
More free tools from Topicary: all free tools · passive voice checker · llms.txt generator
Reference
What the Reading Ease score means
| Score | Reading level | Audience |
|---|---|---|
| 90+ | Very easy | 5th grade — easily understood by an average 11-year-old |
| 80–90 | Easy | 6th grade — conversational English |
| 70–80 | Fairly easy | 7th grade |
| 60–70 | Standard | 8th–9th grade — plain English |
| 50–60 | Fairly difficult | 10th–12th grade |
| 30–50 | Difficult | College — some effort required |
| 0–30 | Very difficult | College graduate — professional or academic |
| below 0 | Extremely difficult | Specialist — dense or technical prose |
The math
The two formulas
Flesch Reading Ease
Reading Ease = 206.835 − 1.015 × (total words ÷ total sentences) − 84.6 × (total syllables ÷ total words)
Higher is easier. Most general documentation should sit at 60 or above.
Flesch-Kincaid Grade Level
Grade Level = 0.39 × (total words ÷ total sentences) + 11.8 × (total syllables ÷ total words) − 15.59
The result is a US school grade. Lower means more people can read it.
Reference
How the Flesch scores work, and how to read them
The Flesch readability tests estimate how hard a passage is to read from two measurable inputs: the average number of words per sentence, and the average number of syllables per word. Longer sentences and longer words both raise difficulty. The tests do not judge vocabulary, logic, or subject matter, only these two structural signals, which is why they are fast to compute and easy to game if you treat them as a target rather than a diagnostic.
Flesch Reading Ease returns a number that is usually between 0 and 100, where higher is easier. A score of 60 to 70 is plain English that most adults read without effort; 30 to 50 signals college-level difficulty; below 30 is dense professional or academic prose. The formula is Reading Ease equals 206.835 minus 1.015 times the words-per-sentence average minus 84.6 times the syllables-per-word average.
Flesch-Kincaid grade level takes the same two inputs and expresses them as a US school grade, so a result of 9.0 means the text suits a ninth grader. The formula is grade level equals 0.39 times the words-per-sentence average plus 11.8 times the syllables-per-word average minus 15.59. Because it shares inputs with Reading Ease, the two always agree on direction: as one improves, the other does too.
The syllable count here is a heuristic. It counts vowel groups, drops a silent trailing “e,” and handles a few common endings, rather than looking each word up in a pronunciation dictionary. That keeps the tool fully client-side and instant, at the cost of a small error margin on unusual words and names. The calculator states that margin openly rather than presenting a false precision.
Read the scores as a prompt, not a verdict. If a page reads harder than its audience needs, the calculator flags your longest sentences first, because sentence length is the input you can most easily change. Splitting a sixty-word sentence into two does more for readability than swapping individual words. And a low score on genuinely technical reference material is often correct; do not flatten precise language to move a number.
Readability holds up better when structure does
A number tells you a page reads hard; it does not tell you which shared passage to fix. Topicary flags long, dense, and duplicated content across every topic so you fix the source once instead of editing the same paragraph in ten places.
Questions
About readability scores
What is a good Flesch Reading Ease score?
For general documentation, aim for 60 or above, which maps to plain English an average adult reads comfortably. Technical and reference material naturally scores lower because of longer words and sentences. Match the target to your audience rather than to a universal number.
What is the difference between Reading Ease and grade level?
Reading Ease is a 0-to-100 scale where higher means easier. Flesch-Kincaid grade level converts the same inputs (average sentence length and average syllables per word) into a US school-grade number, so 8.0 means an eighth grader can read it. They move in opposite directions: easier text has a higher Reading Ease and a lower grade level.
How accurate is the syllable count?
It uses a vowel-group heuristic with silent-e and suffix handling, not a pronunciation dictionary, so it is approximate. On ordinary prose it lands within a few percent of the true count, which moves the grade level by a few tenths at most. Unusual words, names, and acronyms are where it drifts.
Do you store the text I paste?
No. The calculation runs entirely in your browser. Your text never leaves your device and nothing is saved.