As the main web page access modality shifts to mobile devices, evaluations of the impact on underlying networks is required to perform long-term strategic optimizations. In this paper, we characterize individual mobile web page objects by size, cache expiration, and their composition into pages. Employing popular mobile web landing pages, we evaluate their characteristics on an individual and composed page level to derive a model that captures their main facets with respect to object size and caching distributions on a lumped and contextually aggregated page level. We observe that similar distributions can be employed for overall object sizes as well as their composition to web pages, while the cache expiration ages need to be taken into account for different contextual types of web pages. Employing our model, we successfully approximate cache lifetime for the mobile web, demonstrating its use for mobile web performance evaluations. The employed model thus allows network operators to perform broad planning on different time scales.