Coal accounts for approximately 80% of the total operational costs incurred by the steam power plant after maintenance and administration costs. The quality of coal must be compatible with the existing boiler design, therefore the utilization of coal in terms of quality must compatible with the existing boiler design in order to maintain the optimal condition of steam power generation performance. This study aims to analyze the effect of coal quality composition on the generation performance including availability, reliability, efficiency, and profit fuel cost saving. In this study, the low-quality coal and medium-quality coal that obtained from different coal mine suppliers is blended. The calculation result of High heating value (HHV) for boiler design is 4440,45 kcal/kg. Three samples, namely A, B, and C, obtained from coal blending had HHV values of 4437 kcal/kg, 4387.5 kcal/kg, and 4237.5 kcal/kg, respectively. The net plant heat rates obtained from samples A, B, and C are 2447,3 kcal/kWh, 2504,95 kcal/kWh, and 2611,16 kcal/kWh. The value of availability expressed in equivalent availability factor (EAF) and reliability expressed in equivalent force outrage factor (EFOR). The results showed that EAF for samples A, B, and C were 95,36%, 85,81%, and 70,33%; and for EFOR were 0,11%, 5,85%, and 29,67%, respectively. The profit generated from the fuel saving cost for a unit of 280 MW net capacity (DMN), for samples A, B, and C are 2.46 billion rupiahs, 2.43 billion rupiahs, and 2.42 billion rupiahs per day, respectively. The results of this study indicate that slightly different HHV calculation values between boiler design and coal samples can affect the performance of the generation.