Timing exact design conversions from an original field programmable device to an application specific device is disclosed. In a first aspect, a design conversion from a field programmable gate array (FPGA) to an application specific integrated circuit (ASIC) comprises a user configurable element in the FPGA replaced by a mask configurable element in the ASIC. In a second aspect, an FPGA design conversion to an ASIC comprises converting a user configurable memory bit pattern generated by a software tool to program the programmable content of the FPGA to a hard-wired metal pattern for the ASIC.