A complex interface can disorient the user in a mild situation while designing web-based application. Thus, measure should be taken to reduce the complexity and provide reasonable qualities (simplicity, generality and usability) to the user. This paper evaluates Interface Complexity Metric (ICM) between two xml schema languages: World Wide Web Consortium XML Schema (WXS) and Regular Language for Next Generation (RNG) to weigh human insight on the factors affecting effort for comprehending schema documents; taking into account elements and attributes of xml documents; acquired from Web Services Description Language (WSDL). It is probable to lure decisions about the professed qualities; that out of one hundred and twenty (120) schema documents implemented in rng and wxs; rng has the lowest complexity values for almost all the schema documents when compared with wxs because rng exhibits better presentation with high degree of simplicity, generality and usability qualities than wxs. Therefore, this is benefited to developers in assisting them in writing less lengthy code and simplifying software modularization.