Reading Level Checker
Check English readability with Flesch Reading Ease, Flesch–Kincaid grade, Gunning Fog, Coleman–Liau and ARI scores. Instant, free and private.
Type or paste English text to see its readability scores.
Runs entirely in your browser. Your data is never uploaded.
What is Reading Level Checker?
Calculates five standard readability scores for English text: Flesch Reading Ease, Flesch–Kincaid Grade Level, Gunning Fog Index, Coleman–Liau Index and the Automated Readability Index. It also shows the word, sentence and syllable counts behind the scores and a plain-language difficulty band.
How to use Reading Level Checker
- Paste English text (ideally 100 words or more) into the Input box.
- Read Flesch Reading Ease (higher is easier) and the difficulty band below the cards.
- Compare the grade-level scores (Flesch–Kincaid, Gunning Fog, Coleman–Liau, ARI), which estimate the US school grade needed.
- Edit the text and watch the scores change.
Example
The cat sat on the mat.
Flesch Reading Ease 116.1 · Words 6 · Sentences 1 · Syllables 6 · Very easy to read
When to use Reading Level Checker
Use it to compare drafts of English content and aim for a target audience (around 60–70 Flesch for general web copy). The formulas only measure word and sentence length, not meaning or grammar, and they are not valid for other languages – scores for Vietnamese, French or Arabic text are meaningless. Very short texts give unstable results.
How Reading Level Checker works
Words are runs of Latin letters (with internal apostrophes), sentences end at ., ! or ?. Syllables are estimated with a vowel-group heuristic that drops silent endings (-e, -es, -ed). The formulas are: Flesch Reading Ease = 206.835 − 1.015 × (words/sentences) − 84.6 × (syllables/words); Flesch–Kincaid Grade = 0.39 × (words/sentences) + 11.8 × (syllables/words) − 15.59; Gunning Fog = 0.4 × (words/sentences + 100 × complex words/words), where complex words have 3+ syllables; Coleman–Liau = 0.0588 × L − 0.296 × S − 15.8 (L = letters per 100 words, S = sentences per 100 words); ARI = 4.71 × (letters/words) + 0.5 × (words/sentences) − 21.43.
Common Use Cases
- Simplifying website, product or help-centre copy
- Checking that patient information or public notices are easy to read
- Comparing the difficulty of two versions of an article
- Teaching how sentence and word length affect readability
FAQs
What is a good Flesch Reading Ease score?
60–70 corresponds to plain English that most adults read easily. 90+ is very easy, below 30 is very difficult (academic or legal text).
Why is the score above 100 or the grade negative?
The formulas are linear and not clamped. Very short words and sentences produce Flesch scores above 100 and grade levels below 0.
Does it work for other languages?
No. The coefficients and the syllable heuristic are designed for English. Other languages need their own formulas (for example Amstad for German or Fernández Huerta for Spanish), which this tool does not implement.
How accurate is the syllable count?
It is a heuristic and is usually exact or off by one for unusual words, which barely changes the scores for texts of normal length.