Paste your writing and get Flesch Reading Ease, Flesch–Kincaid, Gunning fog and SMOG at once, plus the sentence-length distribution and the exact sentences running long enough to lose a reader.
The spread of sentence lengths appears here as soon as there is text in the box. It is the single most useful picture of a draft: readability formulas average it away, and the average hides both the wall of text and the metronome.
Long sentences are quoted here in full, with their position in the document, so you can go and split them rather than hunt for them.
Every readability score is arithmetic over two things: how long your sentences are and how long your words are. Nothing is hidden behind a model here, so each formula is printed with the numbers it was fed.
The one score on this page where a high number is good. It trades off sentence length against word length, so a page of short sentences built from long words lands in the same place as long sentences built from short ones. Aim for 60 or above if you are writing for a general audience.
The same two inputs rearranged to give a school year instead of a 0–100 score. A result of 9 means a ninth-grade reader can follow it. A grade is easier to act on than a 0–100 score once you know who your reader is, which is why it sits next to the ease score.
Counts complex words rather than syllables. A complex word is three syllables or more, minus proper nouns, hyphenated compounds, and words pushed over the line by an -ed, -es or -ing ending. Those exclusions are part of the fog definition, and they are why fog and SMOG disagree on the same paragraph.
The strictest of the four, and the one health and safety writing tends to be held to, where being understood on the first read is the whole job. It counts every word of three syllables or more with no exclusions, and it is defined on a sample of at least 30 sentences. Below that it is extrapolated, and this page says so rather than quietly rounding.
Sentence length is half of every formula on this page, and it is the half you can change in a minute. The list of sentences over 30 words is above; each one usually contains a full stop that was replaced by a comma.
Syllables per word are the other half. Utilise for use, additionally for also, demonstrate for show. The longest words in your draft are listed under the syllable counter below, so you can start with the ones actually in the text.
A page of twelve-word sentences scores well and reads like a metronome. Burstiness measures the spread, and a healthy passage has short sentences next to long ones. Chase the distribution, not the single number.
The score moves as you edit, so you can see whether a change worked. Then read the paragraph out loud, because the one thing no formula measures is whether the sentence makes sense.
Every readability formula on this page is built on a syllable count, so it is worth being able to check one. Type a word or a whole line and the count appears per word and as a total.
The count is made by rule rather than by dictionary lookup. Vowel groups are counted first, then adjusted: silent terminal e in whale but not in table, silent -ed in walked but not in hundred, syllabic m in rhythm and prism, and the vowel gaps that split create, poem, audience and video into an extra beat. A short table covers genuine irregulars such as business, colonel and Wednesday. It is a heuristic and it will occasionally be wrong; brilliant reads as three.
Paste something into the checker and the longest words in it are listed here with their syllable counts, longest first. Those are the words carrying the grade level.
These formulas date from the middle of the last century, and they measure exactly two properties: how long your sentences run and how long your words are. Everything else is outside their reach.
There is a second thing worth knowing. Flat, even sentence rhythm scores well on every formula here and is one of the properties AI detectors key on, which means writing purely to the grade level can push a human draft toward a machine reading. The AI checker measures that rhythm directly.
For general web writing, journalism and documentation, Flesch Reading Ease of 60 or above and a grade level around 8 or 9. Technical and academic writing sits lower by nature and there is nothing wrong with that. The number worth watching is the gap between where you are and where your reader is.
Because they count different things. Flesch Reading Ease and Flesch–Kincaid use raw syllables. Gunning fog counts complex words but excludes proper nouns, compounds and inflected endings. SMOG counts every three-syllable word and takes a square root, which makes it move more slowly. A spread of two or three grades between them is normal.
Because below that the formulas swing on a single sentence. One 40-word sentence in a 60-word sample moves the grade level by several years, which is a fact about the sample rather than the writing. The counter above tells you how many more words are needed.
SMOG is defined on a sample of at least 30 sentences, and below that the result is extrapolated from too few. It is still shown, with the caveat, so you can watch it move as you write rather than wonder where it went.
By rule, not by dictionary lookup. Vowel groups are counted, then adjusted for silent terminal e, silent -ed and -es endings, syllabic m in rhythm and prism, and the vowel gaps in create, poem and audience. A short table covers genuine irregulars like business and Wednesday. It is a heuristic, and the syllable counter below lets you check any word against it.
No. These formulas measure sentence length and word length. They cannot see whether the argument holds, whether the paragraphs are in the right order, or whether a short sentence is short because it is clear or because it is empty. A high score means the text is easy to decode, which is a precondition for good writing rather than a substitute for it.
Free, no account, and every formula runs in your browser.