An apparatus for classifying a passenger in a vehicle includes a seat cushion for a seat in the vehicle, the seat cushion having an adult detection area and a child detection area. A first chamber is disposed in the adult detection area and a second chamber is disposed in the child detection area. A margin improvement unit includes a pressure sensor configured to measure a first pressure based on a first weight applied to the first chamber and a second pressure based on a second weight applied to the second chamber. The margin improvement unit is configured to output a first adjusted pressure value based on the first pressure and a second adjusted pressure value based on the second pressure. The first adjusted pressure value is greater than the second adjusted pressure value when the first weight is substantially equal to the second weight.