48 Macahilig, H. (2014). A content-based readability formula for … Research article A CONTENT-BASED READABILITY FORMULA FOR FILIPINO TEXTS Heidi B. Macahilig Abstract Several well-known formulas for measuring readability of texts have been developed for use particularly in assessing English texts. For assessing texts in other languages, these formulas were found inadequate or even inappropriate primarily because of the differences in the syntactic structure and lexical nature between and among languages. Thus, some countries have adapted or developed their own formulas to assess reading texts in their respective languages. To date, there is no known formula being widely used to establish the readability of Filipino texts. This study attempted to develop a readability formula that can be used as the standard in determining the readability levels of Filipino academic books required in the different content area subjects, from Kinder to fourth year high school, that use Filipino as the medium of instruction. Keywords: readability, readability formula, Filipino texts INTRODUCTION Readability describes how easy a document can be read and understood. Statistics on readability does not only provide information about the level of difficulty of particular documents