New experimental data from a range of flumes and rivers have been used to test and develop a theoretical model for the thickness of sets of cross strata formed by the migration of subaqueous dunes. The distribution of dune height can be calculated directly from the distribution of cross-set thickness, and vice versa, independently of aggradation rate. Mean dune height is approximately 2.9 (± 0.7) × mean cross-set thickness. The new models relating dune height to cross-set thickness have been tested successfully with data from flumes and from the Calamus and Mississippi Rivers. Furthermore, it is well known that dune height can be related approximately to formative flow depth. Although prediction of flow depth from cross-set thickness and dune height is imprecise, it provides a useful complement to other methods of estimating flow depth from sedimentary information.