The contact pressure between an N95 filtering facepiece respirator (FFR) and the human face plays an important role in FFR performance. In this paper, the effects of several important factors (strap locations on headback, friction, and facial soft tissue material property) on contact pressures are studied using validated N95 FFR/headform finite element models. Sixteen different FFR/headform combinations including six FFRs and five digital headforms (small, medium, large, long/narrow, and short/wide) are studied. For each FFR/headform combination, the facial contact pressure distribution is recorded from the finite element results. The maximum contact pressures from six key areas are recorded for sensitivity study. The results show that the strap locations on the headback produce the largest effect on the maximum contact pressure values and the pressure distribution. The friction and the facial soft tissue material property have limited effects on the maximum contact pressure although they can affect the pressure distribution.