Laminated glass is often used in structures for protection against blast loads. The single-degree-of-freedom model has conventionally been used to design such structures and it continues to be widely in use today. The single-degree-of-freedom model includes mass and load transformation factors, which depend on the deflected shape of the structure. In this study, finite element models are used to derive the deflected shapes and transformation factors. The time-varying deflected shape history is taken into account in this analysis, as this is currently not included in other single-degree-of-freedom models. The analysis was conducted on a range of boundary conditions and aspect ratios along with different loading rates. For low-rate loading, the transformation factors were found not to vary during the deflected shape–time history. For high rate loading, however, the transformation factors were found to vary during the deflected shape–time history therefore requiring their inclusion in the single-degree-of-freedom design methods. These transformation factors were found to be insensitive to aspect ratios.