The Building Materials Cost Index (BCI) is a special purpose index which is based on the Laspeyres formula. It is designated to measure the average rate of change in prices of selected building materials utilized in 9 categories of building in Sabah for 3 regions, namely Kota Kinabalu, Sandakan and Tawau and 8 categories of building in Sarawak for 3 regions, namely Kuching, Sibu and Miri.

The BCI is relevant only for application of the Price Variation Clause in government building contracts. The specifications and weightage pattern for selected building materials by category of building are determined by JKR. Approximately 1700 price quotations are collected monthly for 175 selected building material items.