In a multiprocessor system where each processor has the capacity to executing multiple hardware threads, a method, system, and program for monitoring the percentage usage of the total capacity of the physical processors is provided. A processor capacity monitor calculates a logical usage percentage of each of the available hardware threads. In addition, the processor capacity monitor calculates a physical usage percentage of each of the processors by each of the available threads. Then, the processor capacity monitor multiplies the logical usage percentage and physical usage percentage for each of the threads and sums the result. The summed result is divided by the number of physical processors to determine the percentage usage of the total capacity of the physical processors.