In addition to the Grammarly Readability score, one of the most often used readability scores is the Flesch Kincaid readability test. The Flesch Kincaid test tells consumers what reading level their content is at. The Flesch Kincaid readability test focuses on two metrics to determine the reading level. These two metrics are the average sentence length used and the average syllables per word to determine how easy it is to read.
The formula for the Flesch Kincaid readability test is (1.015 * Average Sentence Length) - (84.6 * Average Syllables Per Word). There is no fixed number that you should aim for. However, there are certain ranges that can give you a good idea of what your score means. If your score is anywhere from 0-50, the reading comprehension is high and can only be read by those with a university reading level. 50-80 means that most high schoolers can comprehend your content. Anywhere from 80-100 means that even consumers at a middle school reading level can comprehend your content.