The article presents a method and results of the implemented measurements of loads of a single carrying idler set on a belt conveyor under working conditions. Currently, identification of the quantity and flow stream of material on the conveyor's belt in mining conditions takes place by means of roller weights. These are devices ensuring identification of temporary efficiency, however, they do not allow precise definition of the scope of real forces to which a single idler is subjected to in the set. Such information can be obtained using a strain gauge measurement method prepared in the Mining Institute of the Wrocław University of Technology. At this point it should be remembered that nothing else but load is a key input parameter in any analyses and design calculations of idlers. The obtained measurement results of loads of carrying idlers and the conducted analyses of performed experimental works find practical application in the process of optimizing construction so lutions of idlers - both with regard to the strength and operating requirements. They may be used to estimate a level of durability of idlers and are a valuable source of information when determining the actual level of their power consumption. The selected examples of such applications have been included in this paper.