Generally, Bond work index is a common method for selecting comminution equipment as well as estimation of grinding efficiency and calculating required power. In the current research, a simple, fast and accurate procedure is introduced to find the rod-mill work index based on the conventional Bond work index. The grinding experiments were carried out on four typical samples of iron, copper, manganese and lead-zinc ore with three test-sieves in specified time periods and aimed to shortening the procedure. Furthermore, the grinding kinetics and mass balance equations were applied to model the standard Bond rod-mill work index. For comparing the standard Bond rod-mill work index and the new modeled method, work index (W-i) and produced fine particles in a cycle (G(i)) for the four samples determined. The performed paired Student's t-test results indicated that the Standard Deviation for G(i) and W-i obtained by the shortened method are respectively 0.50 and 0.58 in respect of traditional Bond method. (C) 2012 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.