Readability Score Calculator

Which formulas does the tool use?

Flesch Reading Ease = 206.835 − 1.015 × (words ÷ sentences) − 84.6 × (syllables ÷ words). Flesch-Kincaid Grade Level = 0.39 × (words ÷ sentences) + 11.8 × (syllables ÷ words) − 15.59. Both are the standard published versions, and both depend only on average sentence length and average syllables per word. Nothing else in the text, such as vocabulary difficulty, structure or topic, affects either score.

Why does a very simple text score exactly 100 and a grade of 1?

Because the results are limited to a range. Reading Ease is held between 0 and 100, and the grade level is never shown below 1, although the raw formulas can go past both ends. "The cat sat on the mat. The dog ran in the park. We like to play." works out to about 116.8 on the formula and −1.7 for the grade, and is displayed as 100.0 and 1. The same applies at the other end: a dense 16-word sentence full of long words comes out as 0.0 for Reading Ease, with a grade of 40.1 because the grade has no upper cap.

How accurate is the syllable count?

It is a rule-of-thumb estimate, not a dictionary lookup. Words of three letters or fewer count as one syllable; for longer words the tool removes a final "ed", an "es" after a consonant other than l, or a consonant plus "e" (other than "le"), and then counts groups of one or two vowels (treating y as a vowel). That works for many words but misjudges others: "beautiful" is counted as 4 syllables, while "created" and "idea" are counted as 1 and 2 where a reader hears 3. Digits are ignored, so "2025" has 0 syllables, which slightly lowers the average. Expect scores to be a few points off a word processor’s.

How does it decide where a sentence ends?

It splits on every run of full stops, question marks and exclamation marks, then discards fragments of two characters or fewer. It does not know abbreviations or decimals, so "Dr. Smith paid $3.5 million in 2025." counts as 2 sentences instead of 1, which makes the average sentence shorter and flatters the score. A heading or bullet that has no closing punctuation merges with the line after it into one long sentence. Add full stops to list items and headings, or paste body text only.

Why can Reading Ease and Grade Level seem to disagree?

They put different weight on the same two averages, then describe the result with different labels. In the 97-word solar-panel passage described on this page, Reading Ease is 51.3, which the tool labels "Fairly Difficult (10th–12th grade)", while the grade level is 8.5 and is described as high school. Both come from short sentences of 9.7 words on average combined with 1.72 syllables per word. Treat the two as approximations and look at the underlying averages rather than the labels.

When does it show suggestions?

There are four rules. A warning appears when the average sentence is longer than 20 words, and another when more than 20% of words have three or more syllables. A general "harder to read than necessary" message appears when Reading Ease is below 60, and a "clear and accessible" message when it is 70 or above. Scores from 60 to 69.9 produce no message unless one of the first two rules fires. The advice about active voice is generic text; the tool does not detect passive sentences or jargon.

Does it work for languages other than English?

Not meaningfully. The constants in the formulas were designed for English, and the syllable routine keeps only the letters a to z, so accented letters are dropped from each word before counting. A word such as "café" is processed as "caf". German, French or Spanish text will return numbers, but they should not be compared with English benchmarks.

Does a high score mean the writing is good?

No. A score describes sentence length and word length only. A text can be made to look easy by chopping it into short sentences without making it clearer, and a technical document can be perfectly appropriate for its readers with a low score. Use the figures to find overlong sentences and stacks of long words, then judge the text yourself.