Nearshore morphodynamic models are computationally demanding, especially when the time scale of interest is weeks or longer. Hence, they often rely on a simple parameterization or non-linear wave theory to estimate the skewed-asymmetric shape of the near-bed, free-stream wave orbital motion, relevant to the prediction of onshore sand transport during mild wave conditions. Recently, Abreu et al. (2010) presented a simple analytical expression for this shape. Here, we present parameterizations to estimate the non-linearity parameter r and phase ϕ in this expression, such that the non-linear orbital motion can be estimated efficiently from values of the significant wave height Hs, wave period T, and water depth h, standard output of nearshore morphodynamic models. The parameterizations are based on a data set of 30.000+ field observations of the orbital skewness Su and asymmetry Au, collected under non-breaking and breaking wave conditions. Consistent with earlier observations, we find that the Ursell number, which includes Hs, T and h, describes the variability in Su and Au well and we use it to link Hs, T and h to r and ϕ. The comparison of our findings to another large field data set suggests that wave non-linearity depends weakly on wave directional spread and that our parameterizations may underestimate Su for narrow-banded swell and (unidirectional) laboratory conditions. Furthermore, the use of the parameterizations is not advised on bed slopes steeper than in our data set (i.e., >1:30).