Readability Checker

What is the Readability Checker?

The Readability Checker is a free tool that scores how easy your text is to read. It calculates the Flesch Reading Ease score and five grade-level formulas, Flesch-Kincaid, Gunning Fog, SMOG, Coleman-Liau and ARI, then averages the grades and lists every sentence over 25 words, so you know exactly which ones to split.

How to use the Readability Checker

1. Paste at least a paragraph. Scores on one or two sentences swing too much to mean anything.
2. Read the Flesch Reading Ease score and the average grade level.
3. Compare the five formulas. Where they disagree, the text is usually short sentences with long words, or the reverse.
4. Work through the long sentences list. Splitting them is the fastest way to raise the score.

What is a good Flesch Reading Ease score?

60 to 70 is plain English, readable by most adults, and the target most style guides set for web copy. 70 and above is easy, the range of popular fiction and good product pages. Below 50 is difficult: academic papers, legal contracts and most enterprise software documentation.

The score rises with shorter sentences and shorter words. It is calculated as 206.835, minus 1.015 times the average words per sentence, minus 84.6 times the average syllables per word.

Does readability affect SEO and AI answers?

Readability is not a Google ranking factor in itself, and Google has said so. What it affects is whether people finish the page and whether a passage can be quoted. Answer engines lift self-contained passages, and a 60 word sentence with three clauses is hard to lift without the sentences around it.

The practical rule is the same for both audiences: one idea per sentence, the answer before the explanation, and no paragraph that only makes sense after the one above it.

Why do the grade level formulas give different answers?

Each formula measures difficulty a different way. Flesch-Kincaid and SMOG count syllables, Gunning Fog counts words of three syllables or more, and Coleman-Liau and ARI count letters, so they never need a syllable estimate. Text with short sentences and long technical words scores easy on the sentence-based ones and hard on the word-based ones. The average smooths that out.

How is the Flesch-Kincaid grade level calculated?

The Flesch-Kincaid grade level is 0.39 times the average words per sentence, plus 11.8 times the average syllables per word, minus 15.59. The result is a US school grade: 8 means a typical eighth grader, about 13 or 14 years old, should be able to follow the text.

It uses the same two inputs as Flesch Reading Ease, weighted differently, so the two move together. It was developed for the US Navy in the 1970s to grade training material, and Microsoft Word still reports it. A grade above 12 does not mean the reader needs a degree, only that the sentences and words are long.

Because sentence length and word length are its only inputs, the grade can be gamed: chopping every sentence in half lowers it without making the ideas any clearer. Use it to find the dense passages, then rewrite them for a reader, not for the number.

What do Gunning Fog, SMOG, Coleman-Liau and ARI measure?

Each estimates a grade level from a different signal. Gunning Fog adds the average sentence length to the percentage of words with three or more syllables, then multiplies by 0.4. SMOG counts the words of three or more syllables, scales them to a 30 sentence sample and takes the square root, which makes it strict about long words. It was built to predict full understanding rather than partial, so it often comes out a grade or two above the others on the same text, and it is often recommended for patient leaflets and health pages.

Coleman-Liau and the Automated Readability Index (ARI) skip syllables entirely. Coleman-Liau uses letters per 100 words and sentences per 100 words; ARI uses characters per word and words per sentence. Counting letters is exact while counting syllables is an estimate, so these two vary least from one tool to another.

Why does my score differ from other readability checkers?

Mostly because checkers count syllables and sentences in slightly different ways. This one uses an English spelling rule rather than a dictionary: it counts the groups of vowels in each word, drops a silent final e and the endings -es and -ed after most consonants, and counts any word of three letters or fewer as one syllable. That is the kind of estimate the formulas were calibrated on, and it is right for most words, but it misses some, and another tool will miss different ones.

Sentence detection matters even more. Here a sentence ends at a full stop, question mark or exclamation mark followed by a space, or at a blank line. A heading or list item with no full stop and only a single line break after it runs into the next line, so it is read as part of one long sentence, which pushes every grade up. Paste body copy only, or put a blank line after each heading and list item. If the words per sentence figure looks far higher than the text feels, lines have been merged.

Because of both effects, the same text can score a few points apart on two sites. Compare scores from one tool over time, before and after an edit, rather than across tools.

How do I check readability in Microsoft Word or Google Docs?

Microsoft Word has it built in but switched off. On Windows, open File, then Options, then Proofing, and tick Show readability statistics. On a Mac the same box is under Word, then Preferences, then Spelling and Grammar. Run Spelling and Grammar from the Review tab, and when it finishes a box shows Flesch Reading Ease and Flesch-Kincaid grade level. Google Docs has no readability score, so paste the text here.

Word gives you two formulas and no sentence list. This checker adds four more grade formulas and lists each sentence over 25 words. To cut those down quickly, the Sentence Shortener rewrites a long sentence in fewer words.