The invention includes a method for determining a software reliability metric, including obtaining testing defect data, obtaining test case data, determining testing exposure time data using the test case data, and computing the software reliability metric using testing defect data and testing exposure time data. The defect data includes software defect records. The test case data includes test case execution time data. A testing results profile is determined using testing defect data and testing exposure time data. A software reliability model is selected according to the testing results profile. A testing defect rate and a number of residual defects are determined by using the software reliability model and the testing results profile. A testing software failure rate is determined using the testing defect rate and the number of residual defects. A field software availability metric is determined using the field software failure rate determined using the testing software failure rate.