Dimensional safety policy checking is an old topic in software analysis concerned with ensuring that programs do not violate basic principles of units of measurement. Scientific and/or navigation software is routinely dimensional and violations of measurement unit safety policies can hide significant domain-specific errors which are hard or impossible to find otherwise. Dimensional analysis of programs written in conventional programming languages is addressed in this paper. We draw general design principles for dimensional analysis tools and then discuss our prototypes, implemented by rewriting, which include both dynamic and static checkers. Our approach is based on assume/assert annotations of code which are properly interpreted by our tools and ignored by standard compilers/interpreters. The output of our prototypes consists of warnings that list those expressions violating the unit safety policy. These prototypes are implemented in the rewriting system Maude.