The Field Programmable Compressor Tree (FPCT) is a programmable compressor tree (e.g., a Wallace or Dadda Tree) intended for integration in an FPGA or other reconfigurable device. This paper presents a design space exploration (DSE) method that can be used to identify the best FPCT architecture for a given set of arithmetic benchmark circuits; in practice, an FPGA vendor can use the design space exploration to tailor the FPCT to meet the needs of the most important benchmark circuits of the vendor's largest-volume clients. One novel feature of the DSE is