Compute text readability score

It also reports the sentence, word, and estimated syllable counts behind those results, making every score inspectable instead of mysterious. Use it to compare drafts, check whether instructions suit an intended audience, or add a consistent readability threshold to an editorial workflow. The calculation is deterministic, fast, and performed without a language model or external service.

Understand what the two scores mean

Flesch Reading Ease and Flesch-Kincaid grade level describe the same basic properties from different perspectives. Reading Ease generally rises when sentences become shorter and words contain fewer syllables. A higher ease result therefore suggests that the sample is simpler to read, while a lower result suggests denser prose. Grade level transforms similar evidence into an approximate United States school grade. A result near eight, for example, suggests that the wording resembles material commonly accessible around eighth grade. Neither number measures whether a claim is correct, whether the writing is engaging, or whether specialist vocabulary is appropriate. They are mechanical signals based on sentence length and estimated word complexity. Treat them as comparison tools, not verdicts about quality. They work especially well when you score several versions of the same message, because a change in the result can reveal that editing made the copy materially simpler or denser. Always interpret the numbers alongside audience knowledge, document purpose, and any terminology that readers genuinely need.

See exactly how the calculation works

The calculator first identifies sentences that end with a period, question mark, or exclamation mark. It then extracts English words and estimates syllables from groups of vowels, with adjustments for common silent endings. From those counts it computes average words per sentence and average syllables per word. Flesch Reading Ease uses the formula 206.835 minus 1.015 times words per sentence minus 84.6 times syllables per word. Flesch-Kincaid grade level uses 0.39 times words per sentence plus 11.8 times syllables per word minus 15.59. Results are rounded to two decimal places, while the underlying sentence, word, and syllable totals remain integers. Syllable counting without a pronunciation dictionary is necessarily an estimate: names, abbreviations, loanwords, and irregular English spellings can differ from spoken pronunciation. That limitation is predictable and applies consistently to every request. For useful comparisons, keep punctuation complete and score samples of similar size and genre. If the input contains no detectable completed sentence, the calculator returns an input error instead of inventing a sentence count and presenting a misleading score.

Use readability scores in real editorial work

Begin with a clear target based on real readers rather than chasing the highest possible Reading Ease value. Product instructions for a broad public audience may benefit from short sentences and familiar words, while a professional standard or scientific abstract may legitimately score as difficult. Paste or submit the complete passage, record both scores, and review the reported counts. Long sentences often offer the quickest editing opportunity: split independent ideas, replace stacked clauses, and move qualifications into a separate sentence. If syllables per word remain high, look for abstract nouns or formal phrases that have accurate shorter alternatives. Recalculate after each meaningful revision and compare the change, but read the text aloud as well. Automated teams can run the same check before publication, flag content outside an agreed range, and send it to an editor rather than automatically rejecting it. Each API request costs $0.002. Because the algorithm is deterministic and uses no network service, identical input produces identical output. This consistency makes it suitable for tests, content pipelines, quality dashboards, and version-to-version audits where unexplained score drift would be undesirable.