Flesch-Kincaid Grade Level Calculator

Seventh to ninth grade for anything aimed at a general audience, including most B2B marketing - the reader's education level is not the constraint, their attention is. Regulated plain-language rules often demand sixth to eighth.

0.39 x (words per sentence) + 11.8 x (syllables per word) - 15.59. Note the weighting: syllables per word carries roughly thirty times the coefficient, but sentence length varies far more in real writing, so in practice sentence length is the lever.

Same inputs, different output. Reading Ease is 0-100 and higher is easier; Grade Level is a school year and higher is harder. They are recalibrations of one another, not independent measurements.

Yes, and routinely does. Insurance policies and academic abstracts often land between 15 and 20. There is no ceiling in the formula.

The US Navy developed it in 1975 to grade training manuals, and it was written into federal plain-language standards from there. That institutional history, not superior accuracy, is why it is the one most often specified in a contract or style guide.

No. The coefficients were fitted to English syllable and sentence patterns. German or Finnish text will return a number, and that number is meaningless. Use a formula calibrated for the language.

Multi-syllable domain terms - implementation, authentication, infrastructure - drive syllables per word up, and the formula cannot tell a jargon word your reader knows cold from one they have never seen. For a specialist audience, a high grade may be correct rather than a problem.

At least 100 words. Below roughly 30, one long sentence moves the grade by several years and the result stops meaning anything.