A computer-implemented method for determining failure in time, FIT, rate, comprising: obtaining circuit data regarding a circuit comprising a plurality of clusters, each cluster comprising a plurality of cells, each cell comprising a first wire segment and a second wire segment; obtaining reliability data describing a failure of the circuit over a pre-determined time period; obtaining a thermal map describing a plurality of temperatures of the circuit; identifying a target failure rate for the circuit; determining, using the circuit data, the reliability data, and the thermal map, a first failure rate for the first wire segment, wherein the first failure rate is a probability that the first wire segment fails in a predetermined amount of time; determining, using the circuit data, the reliability data, and the thermal map, a second failure rate for the second wire segment; determining a circuit failure rate by adding the failure rates corresponding to the first and second wire segments of each of the plurality of cells to obtain a cell failure rate for each cell, adding the cell failure rate for the plurality of cells to obtain a cluster failure rate for each cluster, and adding the cluster failure rate for the plurality of clusters to obtain the circuit failure rate; identifying, using the thermal map and the first and second failure rates corresponding to the first and second wire segments of each of the plurality of clusters, a cluster of the plurality of clusters that disproportionately contributes to the circuit failure rate; in response to identifying the cluster, modifying the wire segments of the cluster to meet the target failure rate; verifying, using the circuit failure rate that the circuit is ready for manufacture; and generating a model of the circuit that describes the first failure rate for the first wire segment and the second failure rate for the second wire segment. obtaining circuit data regarding a circuit comprising a plurality of clusters, each cluster comprising a plurality of cells, each cell comprising a first wire segment and a second wire segment; obtaining reliability data describing a failure of the circuit over a pre-determined time period; obtaining a thermal map describing a plurality of temperatures of the circuit; identifying a target failure rate for the circuit; determining, using the circuit data, the reliability data, and the thermal map, a first failure rate for the first wire segment, wherein the first failure rate is a probability that the first wire segment fails in a predetermined amount of time; determining, using the circuit data, the reliability data, and the thermal map, a second failure rate for the second wire segment; determining a circuit failure rate by adding the failure rates corresponding to the first and second wire segments of each of the plurality of cells to obtain a cell failure rate for each cell, adding the cell failure rate for the plurality of cells to obtain a cluster failure rate for each cluster, and adding the cluster failure rate for the plurality of clusters to obtain the circuit failure rate; identifying, using the thermal map and the first and second failure rates corresponding to the first and second wire segments of each of the plurality of clusters, a cluster of the plurality of clusters that disproportionately contributes to the circuit failure rate; in response to identifying the cluster, modifying the wire segments of the cluster to meet the target failure rate; verifying, using the circuit failure rate that the circuit is ready for manufacture; and generating a model of the circuit that describes the first failure rate for the first wire segment and the second failure rate for the second wire segment. <EOS>