What the Readability Score Analyzer does
This readability checker scores your text with six established formulas - Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog, SMOG, Coleman-Liau and the Automated Readability Index - and shows the word, sentence and syllable counts each one uses. It then ranks your sentences by difficulty, so you can see exactly which ones drag the score down.
Everything is counted in your browser. The formulas are published and simple; what varies between tools is how they count sentences and syllables, so this one shows its counts rather than asking you to trust a single number.
How to use it
- Paste at least 100 words of continuous prose. Headings, bullet lists and tables distort the scores because they lack full sentences.
- Choose Score the text. The Flesch Reading Ease score and its band appear at the top, with all six formulas in the table below.
- Check the counts: words per sentence and syllables per word are the two levers every formula pulls.
- Work through the hardest sentences list. Splitting a long sentence or replacing a four-syllable word usually moves the score more than any other edit.
- Score the revised draft and compare. Copy the scores or download the per-sentence CSV to keep a record.
Reading the results
Flesch Reading Ease runs from about 0 to 100 (it can go outside that range): higher is easier. 60-70 is roughly plain English; academic journal prose often sits between 10 and 30.
The grade-level formulas estimate the US school grade needed to follow the text: grade 8 is about age 13-14. They rarely agree exactly because they weight different things - Coleman-Liau and ARI count letters instead of syllables, Gunning Fog counts words of three or more syllables.
A large gap between formulas is itself informative: it usually means a few very long words or a few very long sentences are doing most of the damage.
Worked example: a five-sentence library notice
The plain-English example has 56 words in 5 sentences and 73 syllables by the tool's count, so 11.2 words per sentence and 1.304 syllables per word.
Flesch Reading Ease = 206.835 - 1.015 x 11.2 - 84.6 x 1.304 = 206.835 - 11.37 - 110.28 = 85.2, which is in the Easy band.
Flesch-Kincaid Grade = 0.39 x 11.2 + 11.8 x 1.304 - 15.59 = 4.37 + 15.38 - 15.59 = 4.2, about a fourth-grade level. The academic abstract example, with long sentences and words such as characterised and randomised, scores below 20 and a grade level in the high teens.
Formulas and scoring rules
- Flesch Reading Ease
206.835 - 1.015 x (words / sentences) - 84.6 x (syllables / words)- Flesch-Kincaid Grade
0.39 x (words / sentences) + 11.8 x (syllables / words) - 15.59- Gunning Fog
0.4 x ((words / sentences) + 100 x (complex words / words))Complex words have three or more syllables, not counting common suffixes.- SMOG
1.0430 x sqrt(polysyllables x 30 / sentences) + 3.1291Designed for samples of 30 sentences or more.- Coleman-Liau
0.0588 x L - 0.296 x S - 15.8L = letters per 100 words, S = sentences per 100 words.- Automated Readability Index
4.71 x (characters / words) + 0.5 x (words / sentences) - 21.43Characters are letters and digits. Scores are shown to one decimal place.
Limitations: what the result does not prove
- Syllables are counted by a spelling heuristic for English. It is right for most words but can miss by one on unusual words and names, so treat every score as an estimate.
- The formulas measure surface features only. A text of short words and short sentences can still be confusing, badly organised or wrong.
- They were calibrated on English school texts. Scores for other languages, code, poetry or bullet lists are not meaningful.
- Writing to a formula can backfire: chopping every sentence in two improves the score but can make an argument harder to follow.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- Kincaid et al. (1975) - Derivation of new readability formulas (US Navy, DTIC) - checked 19 Sep 2026
- Flesch (1948) - A new readability yardstick, Journal of Applied Psychology
Frequently asked questions
What is a good Flesch Reading Ease score?
For material aimed at the general public, 60 or above is a common target, and many plain-language guides aim for 70-80. Academic writing for specialists is usually far lower, and that is acceptable if the audience is expert.
Why do the six formulas give different grade levels?
Each uses different inputs. Flesch-Kincaid and SMOG rely on syllables, Gunning Fog on words of three or more syllables, Coleman-Liau and ARI on letters or characters. Different texts stress each measure differently, so an average is a fair summary.
How many words do I need for a reliable score?
At least 100 words, and more is better. SMOG was designed for 30 sentences; with fewer, the tool marks it as less reliable. Very short samples let one sentence decide the whole score.
Why does my score differ from Microsoft Word's?
Programs split sentences and count syllables differently, especially around abbreviations, numbers, headings and lists. This tool shows its counts so you can see where a difference comes from.
Which sentences should I rewrite first?
Start with the hardest sentences listed: they combine length with long words. Splitting one 45-word sentence often lifts the score more than editing ten average ones.
Is Flesch-Kincaid used in official requirements?
Yes. It was developed for the US Navy in 1975, and some US insurance and government rules have used Flesch or Flesch-Kincaid thresholds for consumer documents. Check the wording of the specific rule that applies to you.
Last reviewed by the A2Z.Tools team against the sources listed above.
