What does a readability formula help to determine?

A readability formula is specifically designed to evaluate the complexity of a written text based on various factors, such as sentence length and word difficulty. This quantitative assessment provides insight into the reading level or grade level of a passage, indicating how easily different audiences can understand the content.

By using readability formulas, writers and editors can ensure that their documents are appropriately tailored for their intended audience, making it a key tool in effective communication. This is particularly important in accessible document creation, as the goal is to foster understanding across diverse reader groups, which might include those with varying literacy levels or language proficiency.

The other options focus on different aspects of writing and design. While the suitability of fonts and colors deals with visual accessibility, the emotional tone pertains to the subjective quality of the content, and the time required to read a document focuses on pacing rather than comprehension level. These elements are important, but they do not directly relate to the primary function of a readability formula.