Textbook writers, Chinese language teachers, and test designers need to ensure readability of the texts they use or intended to use. They often resort to "expert judgements" based on professional experience rather than apply objective measures. This happens because there is a lack of suitable readability formulas like those established for English. Moreover, in the Singaporean context where Chinese language is taught at a lower level (referred to as a Second Language or Mother Tongue Language), readability formulas developed for Chinese as a First Language for use in, for example, the Chinese mainland and Taiwan, are not suitable for use in Singapore (and other places where Chinese is learned as a heritage language). The present study made use of extant Chinese language textbooks as the source of data and created three readability formulas for Chinese as a Second Language. Predicted grade levels were then compared with the original grade levels of 100 selected texts at Primary 1 to Secondary 4 levels. The formula for the full text was found to be most effective when compared with the two for shorter versions of the texts. Prediction was more accurate when applied to the texts for Primary 1-6 students than to the texts for Secondary 1-4 students. The formula was found to be convenient to use as it entailed just three language features which could be easily hand-calculated, i.e., the number of Chinese characters, the number of words, and the average sentence length. Practical use and limitations of the formula are discussed.