Flesch Reading Ease Calculator

60 to 70 for general web writing, marketing copy and documentation. Below 50 you are writing for a university-educated reader whether you meant to or not. Above 80 can read as simplistic for a technical audience.

206.835 - 1.015 x (words per sentence) - 84.6 x (syllables per word). That is the whole formula. It measures sentence and word length, nothing else.

Same two inputs, opposite direction. Reading Ease gives a 0-100 score where high is easy. Flesch-Kincaid gives a US school grade level where high is hard. Use Reading Ease for a target to hit, Flesch-Kincaid when someone asks for a grade number.

No. The formula cannot see whether a sentence is true, clear or worth reading - only how long it is. A page of disconnected short sentences scores 90 and reads badly. Treat it as a check on density, not a quality grade.

Not as a ranking factor. It affects whether people finish the page, and Google has said plainly that there is no readability score in the ranking systems. Write for the reader; the score is a proxy for whether you did.

The formula counts sentences by terminal punctuation. Adding a full stop splits one long sentence into two shorter ones, which moves the score more than any word swap will.

With the standard vowel-group heuristic that every browser-based implementation uses - it groups adjacent vowels and strips common silent endings. It is right the large majority of the time and occasionally off on unusual names, which is enough for a score you are reading as a band, not a decimal.

At least 100 words. Under about 30 words a single long sentence swings the result by twenty points or more, so short snippets give you noise.