Check the readability of your writing
The Readability Checker measures how easy your text is to read using six established formulas: Flesch Reading Ease, Flesch–Kincaid Grade Level, Gunning Fog, SMOG, Coleman–Liau and the Automated Readability Index. It also averages the five grade-level scores into one number and highlights sentences over 25 words and words of three or more syllables, so you can see exactly what to simplify.
Clear writing gets read. Government plain-language guidelines, health information leaflets, customer emails, school materials and web content are commonly aimed at around a US grade 8 reading level — roughly a 13- to 14-year-old. Paste your draft, check the scores, edit, and watch them change as you type. Your text is analysed in the browser and never uploaded.
How to use the Readability Checker
- Paste or type your text into “Your text”. At least 100 words gives the most dependable scores.
- Read the Flesch Reading Ease score at the top: higher means easier. The guide table below the tool highlights the band your text falls in.
- Check the grade-level cards. Each shows the US school grade and approximate reader age; “Average grade level” combines all five.
- Scroll to the highlighted copy of your text: yellow marks sentences over 25 words, underlined words have three or more syllables.
- Split long sentences and swap complex words for simpler ones, then press “Copy report” to save the scores.
Readability Checker features
Six formulas at once
Flesch Reading Ease plus five grade-level indices, calculated from the same word, sentence and syllable counts so they are directly comparable.
Visual highlighting
Long sentences and complex words are marked directly in your text, which shows where the score comes from.
Smart sentence detection
Abbreviations such as Dr., e.g., p.m. and U.S. and initials like “J. K.” do not end sentences, and line breaks separate headings and list items.
Detailed statistics
Words, sentences, syllables, words per sentence, syllables per word, complex-word percentage, long-sentence count and reading time.
Live and private
Scores update as you type and the analysis never leaves your device.
The readability formulas
Every formula combines sentence length with word difficulty. W = words, S = sentences, Sy = syllables.
| Formula | Calculation | Output |
|---|---|---|
| Flesch Reading Ease (1948) | 206.835 − 1.015 × (W ÷ S) − 84.6 × (Sy ÷ W) | Score, usually 0–100; higher is easier |
| Flesch–Kincaid Grade (1975) | 0.39 × (W ÷ S) + 11.8 × (Sy ÷ W) − 15.59 | US school grade |
| Gunning Fog (1952) | 0.4 × [(W ÷ S) + 100 × (complex words ÷ W)] | Years of education |
| SMOG (McLaughlin, 1969) | 1.043 × √(polysyllables × 30 ÷ S) + 3.1291 | US grade |
| Coleman–Liau (1975) | 0.0588 × L − 0.296 × S100 − 15.8 (L = letters per 100 words, S100 = sentences per 100 words) | US grade |
| Automated Readability Index | 4.71 × (characters ÷ W) + 0.5 × (W ÷ S) − 21.43 | US grade |
How syllables and complex words are counted
Syllables are estimated with documented rules rather than a dictionary: count groups of vowels (a, e, i, o, u, y), drop a silent final “e”, treat “-es” and “-ed” as silent unless they follow a sound that needs them (boxes, wanted), count a consonant + “le” ending as a syllable (ta-ble), treat “y” before a vowel as a consonant (play-ing), split vowel pairs that are usually pronounced separately (ra-di-o, ac-tu-al, i-de-a), and use a short list of exceptions for common irregular words. This matches dictionary counts for most everyday English words but can be off by one for unusual ones, which shifts scores only slightly over a full text.
For Gunning Fog, a complex word has three or more syllables but is not a capitalised proper noun, a hyphenated compound, or a two-syllable word made longer only by -es, -ed or -ing. SMOG counts every word of three or more syllables. Numbers count as one word of one syllable.
How to improve your readability score
- Aim for an average of 15–20 words per sentence, and split any sentence over 25 words.
- Prefer short, familiar words: “use” instead of “utilise”, “help” instead of “facilitate”, “about” instead of “approximately”.
- Turn abstract nouns back into verbs: “we decided” rather than “a decision was made”.
- Use lists and headings for steps and options, and keep one idea per paragraph.
- Spot repeated jargon with the Word Frequency Counter and check length with the Word Counter.
Readability Checker FAQ
What is a good readability score?
For general audiences, aim for a Flesch Reading Ease score of 60–70 or higher and a grade level of about 8. Technical and academic writing often scores lower, which is fine when the readers are specialists.
How is the Flesch Reading Ease score calculated?
It is 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Long sentences and long words lower the score. Most text falls between 0 and 100, but very simple or very dense text can go outside that range.
Why do the different formulas give different grades?
They weigh different features: Flesch–Kincaid and SMOG rely on syllables, Coleman–Liau and ARI on letters per word, and Gunning Fog on the share of complex words. Looking at the average grade level smooths out their differences.
What does grade level mean outside the US?
Grade levels follow US school years. Add about five to get the reader’s age: grade 8 is roughly age 13–14, which is Year 9 in England and Wales or Class 8 in India.
Does the readability checker work for other languages?
The formulas and syllable rules are designed for English. Other languages have different word and syllable lengths, so the numbers will not be meaningful.
Is my text saved anywhere?
No. The readability checker runs entirely in your browser; nothing is uploaded, logged or stored.