Background Calculated-PRA (CPRA) is derived by virtually matching a recipient’s antibody profile against HLA antigens of a representative donor pool of a geographical region. Materials and Methods An android application–based CPRA calculator was created from HLA typing data (A/B/DR loci) of 712 consecutive living donors spanning over last 10 years from an organ-sharing region in Kerala. Only an open-source software was used. Results Our HLA data, compared with the National Marrow Donor Program (NMDP) 2011 database, show that the most common haplotype frequencies show comparable positions in order of prevalence. Available online PRA calculators like OPTN and Canadian CPRA show significant differences in PRA estimation when used in our population. This calculator provides a more accurate and realistic estimate of sensitization against the representative donor pool. Conclusion This CPRA tool can be customized for any allocation region using portable open-source software. The donor pool can be updated continually by populating data from multiple regional centers.