The main quality indicator of kukersite is calorific value. Determining of this indicator is time and labor consuming. Using simple quality indicators, such as ash content or burning matter range, has not been. adequate enough. The current paper shows that in some cases, when mining technology and structure of extracted material is constant, the quality of oil shale can be evaluated by the content of burning matter, In the case of oil shale resource calculations, the specific weight of the mineral is not measured but evaluated by calorific value. This method does not take into account the relationship between clay and lime minerals in the layers. The deviations front calculated resource,figures have been noticed in mining practice. The error of this method is evaluated, and recommendations for recalculating oil shale resources are given.