An improved weight estimation apparatus in which a closed, multiple cell elastomeric bladder filled with fluid is installed in the foam cushion of a vehicle seat bottom, with at least one pressure sensor installed in a closed exit port of the bladder. The multiple cells of the bladder are formed by a pattern of spot welds between the top and bottom layers of the bladder, creating an array of generally circular or hexagonal cells between which the fluid can freely flow. The array of cells maximizes the pressure response for improved sensitivity, and minimizes the amount of fluid required to detect occupant weight, thereby minimizing the weight of the fluid-filled bladder. The pattern of spot welds in the vicinity of the pressure sensing location may be altered to reduce sensitivity to forces applied in proximity to the exit port. In a first embodiment, a more dense pattern of spot welds is provided in the vicinity of the exit port, while in a second embodiment, continuous welding is used to form a pattern of closed fluid-free pockets in the vicinity of the exit port.