A forward model was used to study the relationship between gravitational compaction and tectonic subsidence in an idealized, one-dimensional sedimentary basin. Gravitational compaction was modelled by a non-linear, partial differential equation that gives the sediment porosity as a function of time and burial depth. The sediments were described in terms of soil mechanics laws for mechanical compressibility and permeability. The sedimentation rate appeared as a boundary condition at the depositional surface. Tectonic subsidence was coupled to the compaction model via an isostatic balance based on Airy's hypothesis. Parameter studies showed that changes in the sedimentation rate and in the sediment compressibility can lead to variations from 454 to 781 m in the subsidence for sediment thicknesses in the range 6.9–7.9 km. The forward model was used to assess how well standard backstripping methods reconstructed subsidence history from present day porosity versus depth data. Standard backstripping can bias the tectonic subsidence by 100–200 m, comparable with inferred eustatic variations. This bias results because the porosity depends not only on burial depth but also on time. By using deterministic models to describe gravitational compaction, mechanical properties can be used to better constrain compaction history, thus improving the accuracy of reconstructed tectonic subsidence curves.