In this paper, we present an experimental and analytic procedure for determining the effective leak and vent areas of a full size airbag. Three different bag materials were tested and analyzed: 420 D (72 X 46), 420 D (49 X 49), and 840 D (32 X 32). An airbag model in CAL3D was used to inversely compute the effective leak area based on experimental data. Regression analysis was then performed to find the best fit of mathematical models for estimating effective leak areas as a function of pressure. Following a similar procedure, the effective vent area was also analyzed. Data are presented for a passenger bag and a driver bag. These results are useful for occupant dynamics simulations.