Sintering trajectories were simulated for different initial grain sizes assuming grain-boundary diffusion as densification mechanism and either pore drag or intrinsic grain-boundary mobility as grain growth mechanisms. Computation of comparable sintering trajectories for initial grain sizes between 10<space>nm and 250<space>nm necessitated an adjustment of the isothermal sintering temperature. Conditions where one of the two coarsening mechanisms prevails were determined and shown to depend on density, grain size, and the ratio S of the rate constants related to the two coarsening mechanisms, but little on the dihedral angle. All computed sintering trajectories have a common shape, being very flat at low densities and exhibiting most grain growth in the last 5% of densification before reaching their end-point density. Depending on the difference between the activation energies related to the dominant densification and coarsening mechanisms, a reduction in grain size might be beneficial for densification.