The supply of raw materials is an important asset for the company. Inaccuracies in the preparation of raw material supplies can have an impact on the production process and incur greater inventory costs. Therefore, more accurate planning of raw material supplies is needed so that there are no excesses or shortages of stock. This research aims to find out inventory policies, control the availability of gypsum and trass raw materials, and minimize inventory costs. In planning gypsum and trass inventory control, the Material Requirement Planning (MRP) method will be used. MRP methods used in this paper are Lot-for-Lot (LFL), Economic Order Quantity (EOQ), and Periodic Order Quantity (POQ) as a comparison for companies in planning gypsum and trass inventory. Calculations are carried out theoretically as well as with a realistic approach to the terms of the number of purchases of the company. For gypsum material, the minimum supply is generated by the LFL method, both theoretically and with a realistic approach. Theoretically, the resulting savings for gypsum are 2.80%, and with a real approach the resulting savings of 1.88%. For trass materials, the minimum supply is also generated by the LFL method. Theoretically, the resulting savings for trass are 0.78% and with a real approach, the resulting savings are 0.11%. It can be proposed to the company to apply the LFL method to obtain the minimum inventory costs with the amount of inventory corresponding to the number of net needs in the corresponding period.