Selected Text Readability is a free Chrome add-on developed by yndajas.dev. This handy tool allows users to estimate the readability of selected text on a webpage. With just a few simple steps, users can quickly assess the grade level required to understand the text.

To use Selected Text Readability, users need to highlight the desired text on a webpage and click on the extension icon. The add-on will then analyze the text and provide information about the estimated US grade level required. The calculation is based on the Coleman-Liau Index, a widely-used formula for measuring readability.

The add-on offers a wide range of grade levels, from pre-school to graduate. It also provides a non-US equivalence guide, giving users a rough idea of how US grades map to ages and UK school years. For those interested in learning more about the index and alternative methods, the add-on includes additional information and limitations.

Selected Text Readability is a useful tool for anyone who wants to quickly assess the readability of selected text. Whether you're a student, researcher, or simply curious about the complexity of a particular passage, this add-on provides a convenient way to measure and understand the grade level required.