Readability Checker
Estimate reading ease and grade level from sentence and word patterns. Your work stays on this device whenever possible.
How to use Readability Checker
- Paste the passage into "Paste passage to evaluate readability".
- Press "Calculate readability" to open the dashboard of eight tiles.
- Read "Flesch Reading Ease" with its label, then compare "Flesch-Kincaid Grade", "Gunning Fog Index", "Coleman-Liau Index", "SMOG Index" and "Automated Readability (ARI)".
- Check "Target Audience", "Complex Words (%)" and the "Readability Alert" listing up to five sentences over 25 words.
- Use "Download Report (TXT)" or "Export Metrics (CSV)" to keep the numbers.
Worked example
Enter "The cat sat on the mat." It has 6 words, 1 sentence, 6 syllables and 0 complex words. Reading Ease is 206.835 - 1.015 x 6 - 84.6 x 1 = 116.1, shown clamped as 100.0 (Very Easy). Flesch-Kincaid shows Grade 1.0 (raw -1.45), Fog 2.4, Coleman-Liau -4.1, SMOG 3.1 and ARI -5.1.
When to use this tool
- Checking that a help-centre article suits a general audience.
- Comparing two drafts of the same introduction to see which is easier.
- Finding the over-long sentences in a policy document.
Important limitations
Readability formulas rely on statistical syllable and sentence heuristics calibrated for English prose. Technical jargon and specialized acronyms may distort grade level estimates.
Frequently asked questions
Why do the six formulas give different answers?
Each weights sentence length, syllables and letters differently. ARI and Coleman-Liau use letter counts, not syllables, so they diverge from Flesch and Fog on jargon-heavy text. Read them as a range, not a single verdict.
How are syllables counted?
By a vowel-group heuristic for English. Words of three letters or fewer count as one syllable, and names, acronyms or non-English words are frequently miscounted, which shifts every syllable-based score.
Is the SMOG value valid on a short passage?
SMOG was designed for samples of about 30 sentences. Here it is applied to any length, so a two-sentence text produces a rough figure only.
Are the scores bounded?
Reading Ease is clamped to 0-100 and Flesch-Kincaid grade never falls below 1. Coleman-Liau and ARI are not clamped and can go negative on very simple text.
What counts as a sentence?
Text ending in . ! or ?, plus any trailing fragment. A bulleted list with no punctuation becomes one long sentence and pushes the scores up.