Readability Checker
Paste your writing to see how easy it is to read. You get six standard readability scores, the US grade level, sentence and word statistics, and the long sentences and complex words highlighted.
SMOG was designed for samples of 30 sentences or more. With fewer sentences it is scaled up and is less reliable.
Text statistics
Sentence highlights
What the Flesch score means
| Score | Difficulty | US school level | Typical reader |
|---|
How to use the Readability Checker
- Paste your text into the box. A paragraph or more gives the most reliable scores.
- Press Check readability (the scores also update as you type).
- Read the Flesch Reading Ease score: higher is easier. 60–70 is plain English for most readers.
- Compare the grade levels from Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau and ARI, and their average.
- Fix the highlighted sentences: split long ones and swap complex words for shorter ones, then check again.
Readability formulas used
W = words, S = sentences, Sy = syllables, C = complex words (3 or more syllables), L = letters and digits.
| Score | Formula | Reading the result |
|---|---|---|
| Flesch Reading Ease | 206.835 − 1.015 × (W ÷ S) − 84.6 × (Sy ÷ W) | 0–100, higher is easier |
| Flesch-Kincaid Grade | 0.39 × (W ÷ S) + 11.8 × (Sy ÷ W) − 15.59 | US school grade |
| Gunning Fog | 0.4 × [(W ÷ S) + 100 × (C ÷ W)] | Years of education needed |
| SMOG | 1.0430 × √(C × 30 ÷ S) + 3.1291 | US grade, made for 30+ sentences |
| Coleman-Liau | 0.0588 × L100 − 0.296 × S100 − 15.8 | US grade; L100 = letters per 100 words, S100 = sentences per 100 words |
| Automated Readability Index | 4.71 × (L ÷ W) + 0.5 × (W ÷ S) − 21.43 | US grade |
The average grade level is the mean of the five grade formulas (Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau and ARI).
How the syllable counter and sentence splitter work
The tool uses a transparent, rule-based syllable counter so you can predict its results:
- Lower-case the word, remove accents and keep only the letters a–z. Numbers count as one syllable.
- Words of three letters or fewer have one syllable.
- Drop silent endings: a final e after a consonant (but keep -le after a consonant, as in table); -es after a consonant other than c, g, h, s, x or z (makes → 1, but boxes → 2); and -ed after a consonant other than t or d (jumped → 1, but wanted → 2).
- Ignore a leading y, which is a consonant there (yellow).
- Count the groups of consecutive vowels (a, e, i, o, u, y). Every word has at least one syllable.
Examples: cabin 2, people 2, visitors 3, understanding 4, conservation 4. A sentence ends at ., !, ? or … followed by a space or the end of the text, or at a blank line. Common abbreviations such as Mr., Dr., e.g. and single initials do not end a sentence. Words are runs of letters and digits; apostrophes stay inside a word (don't is one word) and hyphenated words count as separate words.
Worked example
Take the two sentences “The cat sat on the mat. It was happy and warm.” There are 11 words, 2 sentences and 12 syllables (only happy has two). So W ÷ S = 5.5 and Sy ÷ W = 1.091.
- Flesch Reading Ease = 206.835 − 1.015 × 5.5 − 84.6 × 1.091 = 109.0 (scores above 100 are possible for very simple text).
- Flesch-Kincaid Grade = 0.39 × 5.5 + 11.8 × 1.091 − 15.59 = −0.6, below first grade.
- Gunning Fog = 0.4 × (5.5 + 0) = 2.2, since there are no complex words.
Tips to make text easier to read
- Keep sentences short. Aim for an average of 15 to 20 words, and split anything over 25.
- Prefer short words. “Use” instead of “utilize”, “help” instead of “facilitate”, “about” instead of “approximately”.
- Use the active voice. “The team fixed the bug” is shorter and clearer than “The bug was fixed by the team”.
- One idea per sentence. If a sentence has several commas and “and”s, it is often two sentences.
- Don't over-optimize. Formulas can't judge meaning or structure. Technical terms your readers know are fine.
Frequently asked questions
What is a good Flesch Reading Ease score?
For general web content and marketing, aim for 60 to 70 (plain English, about 8th to 9th grade). Scores of 70 and above are easy for most adults. Academic and legal texts often score below 30.
What is the difference between Flesch Reading Ease and Flesch-Kincaid Grade?
Both use the same two inputs, average sentence length and average syllables per word. Reading Ease gives a score from about 0 to 100 where higher is easier, while the Flesch-Kincaid Grade converts the result to a US school grade, where lower is easier.
Why do the grade levels differ between formulas?
Each formula measures difficulty differently. Flesch-Kincaid and SMOG rely on syllables, Gunning Fog on the share of words with three or more syllables, and Coleman-Liau and ARI on letters per word. Looking at the average grade gives a balanced view.
How are syllables counted?
With a documented rule set: vowel groups are counted after removing silent endings such as a final e, -es and -ed. It matches dictionary syllable counts for most common words, but no automatic counter is perfect, so scores can differ slightly from other tools.
How much text do I need?
Use at least 100 words for a meaningful result. SMOG was designed for 30 sentences, so with fewer sentences the tool scales the count and shows a note that the result is less reliable.
Is my text stored or uploaded?
No. All calculations run in your browser on this device and nothing is sent to a server.