Readability Score Calculator
Readability Score Calculator: Applies English word, sentence, and syllable heuristics to return Flesch Reading Ease, Flesch-Kincaid Grade, and Automated Readability Index; it is not a comprehension test.
About this readability score calculator
Applies English word, sentence, and syllable heuristics to return Flesch Reading Ease, Flesch-Kincaid Grade, and Automated Readability Index; it is not a comprehension test Applies Unicode-compliant text transformations and parsing directly in the browser tab without data leakage.
Text processing & transformation mechanics
Calculates Flesch Reading Ease, Flesch-Kincaid Grade, and Automated Readability Index from English-letter word matches, a sentence-ending punctuation heuristic, and an English syllable heuristic. It rejects input with no English word. For accepted input it returns JSON counts for words, sentences, syllables, and letters plus the three scores rounded to one decimal.
Worked text manipulation example
Scenario: Calculate the implemented English readability heuristics for a short sentence.
Sample input:
Processing: Match English-letter words, count sentence endings, estimate syllables, and apply the three formulas.
Illustrative output:
Character encoding & string length boundaries
This is an English heuristic, not a comprehension test. Input with no English word is rejected. Non-English text, abbreviations, names, code, and unusual punctuation can distort the counts and scores of accepted input.
Text formatting and transformations in Readability Score Calculator preserve character integrity. Check edge cases such as multi-line inputs and special characters before downstream use.
In-memory text processing boundary
String operations and Unicode manipulations in Readability Score Calculator execute entirely in local browser memory without transmitting input text.
Unicode Consortium & text formatting standards
Unicode Consortium standard annexes (UAX) and character encoding specifications:
- Flesch Reading Ease, Flesch-Kincaid Grade, and Automated Readability Index formulas.
- Local English A–Z word matching, punctuation-based sentence count, and syllable heuristic; not a standardized comprehension test.
Readability Score Calculator verification · Audit standards
How to use it
- Paste English prose, for example: This is a test.
- Click Run locally; the tool rejects an input with no English word. Otherwise it matches English-letter words, counts sentence-ending `.`, `!`, and `?` runs, estimates syllables, and applies the three formulas.
- Read the JSON `words`, `sentences`, `syllables`, `letters`, `fleschReadingEase`, `fleschKincaidGrade`, and `automatedReadabilityIndex` fields.
Frequently asked questions
What does the readability-score calculator accept and calculate?+
It extracts words made of A–Z letters with an internal apostrophe, curly apostrophe, or hyphen allowed; counts sentence-ending punctuation; estimates syllables; counts letters exactly; and returns `words`, `sentences`, `syllables`, `letters`, `fleschReadingEase`, `fleschKincaidGrade`, and `automatedReadabilityIndex`. Empty, Chinese-only, numeric-only, and any other input with no English word are rejected with `Enter text containing at least one English word.`.
Can I try a concrete input?+
Enter `This is a test.` and choose Run locally. It returns `words: 4`, `sentences: 1`, `syllables: 4`, `letters: 11`, and `fleschReadingEase: 118.2`.
Are syllable counts dictionary-verified?+
No. The tool estimates syllables from English vowel groups and a small silent-ending rule. Names, abbreviations, other languages, and pronunciation exceptions can produce different counts.
Does a readability score measure truth or writing quality?+
No. These formulas measure selected surface statistics. Accuracy, tone, accessibility, domain expertise, persuasion, and suitability for a particular reader require separate review.