爺爺奶奶 - 親戚稱呼計算機 - Relative Cal is an Android app developed by LouisthLabs, which aims to help Chinese users find the correct titles for their relatives. The app features a simple interface with 10 buttons that represent the most common family members. By pressing these buttons in the correct order, users can find the direct title for their relative.

For example, if a user wants to know how to address their wife's older brother, they can input 【妻】【的】【兄】, and the app will provide the correct answer, which is 【大舅子】. The app also includes buttons to add layers of relationship, calculate the final title, clear the input, and view alternative titles.

Overall, 爺爺奶奶 - 親戚稱呼計算機 - Relative Cal is a useful tool for Chinese users who need to know the correct titles for their relatives.