Static pressure of rough rice, wheat, corn, milled rice and soybean were investigated at different moisture contents and airflow rates. The pressure gradient along the depth of the packed bed was found to vary linearly. The static pressure was also found to depend on the airflow rate and moisture content of the materials, increasing with increase in any of the parameters. The static pressure was observed to satisfy the Ramsin equation. However, the constant, α was observed to be dependent on the moisture content of the material, hence the moisture content was added to this equation. Taking into account of the moisture content of the material enabled the variation of the static pressure between the materials to be explained to a reasonable accuracy.