Absolute hydrogen capacities of nanoporous storage materials cannot be accessed using conventional gas sorption experiments, but can be estimated by modelling experimental excess data. We have collected excess hydrogen gas isotherm data at 77K on well-characterised reference materials of porous, activated carbon and modelled the isotherms using a methodology developed in-house to estimate of the absolute hydrogen content of our materials with respect to pressure, but the results are in need of verification by direct measurement. We aim to use TOSCA in a novel way to directly measure the total amounts of hydrogen stored in porous hydrogen storage materials, to aid in design of practical storage systems.The absolute amounts will also be compared to predictions from solid-state NMR data (provided by collaborators at the Univ. of North Carolina).