The Units library provides a means of working with units of measurement at runtime, including conversion to and from strings. It provides a small number of types for working with units and measurements and operations necessary for user input and output with units. This software was developed for use in LLNL/GridDyn, and HELICS and is currently a work in progress (though getting close). Namespaces, function names, and code organization is subject to change though is fairly stable at this point, input is welcome.