Readability Checker

How to use the readability checker

1. Paste or type your text in the box, or use Open file for a plain-text file (.txt, .md and similar). Example loads a short sample.
2. Read the Flesch reading ease score at the top and its label, such as Standard or Fairly difficult. The note under the figures gives the matching school level.
3. Compare the five grade-level scores beside it. When they roughly agree, the estimate is solid; when they differ by several grades, look at the counts below them to see why.
4. Scroll to Long sentences (over 25 words). Each sentence is listed with its word count (up to 20), so you can split them first.
5. Edit and check again. The scores update as you type, which makes it easy to compare a sentence before and after a rewrite.

Use at least a few paragraphs. A single sentence gives extreme scores in either direction.

The six scores and what they measure

All six formulas use the same few counts, shown in the second row: words, sentences, syllables, words per sentence, syllables per word and complex words (words of three or more syllables).

The Flesch scores and Gunning fog depend on syllables. Coleman–Liau counts letters and the Automated Readability Index (ARI) counts letters and digits instead, because characters can be counted exactly. That makes them a useful cross-check when the syllable estimate is off. Microsoft Word shows only the first two scores.

SMOG was designed for samples of 30 sentences. On shorter texts the checker still calculates it but adds needs 30+ sentences, because the result is less reliable.

How the checker counts

• Words are runs of characters between spaces that contain a letter or digit, as in the word counter. Well-known, don’t and 12.5% are one word each; a lone dash is not a word.
• Sentences end with ., !, ? or … followed by a space or the end of the text. Dr., e.g., p.m., decimals and initials do not end a sentence, so “Dr. Smith arrived at 3 p.m. on Monday. He left early.” is 2 sentences. Text with no end punctuation counts as one sentence.
• Empty lines and list items end sentences; single line breaks do not. A heading followed by an empty line is its own sentence, and each line that starts with -, *, • or a number such as 1. counts as a separate sentence even without a period. A single line break between ordinary lines is ignored, because text copied from PDFs breaks lines mid-sentence, so a heading directly above a paragraph runs into its first sentence. Very short headings and list items count as short sentences and push the score up, so check body text without them.
• Syllables are estimated with English spelling rules: groups of vowels, silent final e, silent -ed and -es, and a list of exceptions such as every (2), business (2) and interesting (4). Hyphenated words count part by part (well-known is 2), and a number such as 2026 counts as one syllable. Check any word with the syllable counter; how to count syllables explains the rules.
• Complex words are all words of three or more syllables. Gunning’s original rule leaves out proper nouns and words that reach three syllables only through -es, -ed or -ing; this checker counts them, so its fog score can be slightly higher than a hand count.

Worked examples

These figures come from running the checker’s own code.

The last two rows say the same thing. The first uses one 19-word sentence with 8 complex words; the second uses two short sentences and none.

A longer rewrite shows how all the scores move together:

We will be implementing a comprehensive reorganization of the customer
support department, which will necessitate additional training for all
representatives. Representatives should familiarize themselves with the
documentation immediately.

Flesch −24.9 (Very difficult), Flesch–Kincaid grade 20.2, 14 words per sentence, 12 complex words out of 28.

We are changing how support works. Every agent will get extra training.
Please read the new guide today.

Flesch 83.2 (Easy), Flesch–Kincaid grade 3.1, 6 words per sentence, no complex words.

What to change to raise the score

The Flesch reading ease formula gives almost all its weight to two things, so improvements come from the same two places:

1. Shorter sentences. Split sentences in the long-sentence list at and, but, which or a semicolon. The sentence counter shows the average length as you edit.
2. Shorter words. Swap utilize for use, necessitate for need, at your earliest convenience for soon. Each syllable per word you save moves the Flesch score by 84.6 points on average, far more than a word per sentence (1.015 points).
3. Fewer nominalizations. Implementation of, reorganization of and similar nouns add syllables; the verb (implement, reorganize) is shorter and usually clearer.

Do not chase the number at the cost of meaning. A formula cannot tell whether the ideas are in a sensible order, whether the reader knows the subject, or whether a short word is obscure. Technical terms your readers expect, such as database or medication, are fine even though they lower the score. For the background on what each band means and typical targets by type of text, see the guide to the Flesch reading ease score.

When a readability check helps

• Web pages and product copy for a general audience, where a score of 60 or more keeps the text easy to scan.
• Health and government information, where SMOG is widely used to check that leaflets suit readers with limited schooling.
• Emails, policies and instructions at work, to catch the 40-word sentence before it goes out.
• School writing, to see whether an essay reads at the expected grade or is weighed down by long sentences.

Questions