Soft errors due to cosmic particles are a growing reliability threat for VLSI systems. The vulnerability of FPGA-based designs to soft errors is higher than ASIC implementations since the majority of chip real estate is dedicated to memory bits, configuration bits, and user bits. Moreover, single event upsets (SEUs) in the configuration bits of SRAM-based FPGAs result in permanent errors in the mapped design. In this paper we analyze the soft error vulnerability of FPGAs used in information systems. Since the reliability requirements of these high performance information subsystems are very stringent, the reliability of the FPGA chips used in the design of such systems plays a critical role in overall system reliability. We present an analytical approach (versus fault injection) for soft error rate estimation in FPGA-based designs. We also validate the projections produced by our analytical model using field error rates obtained from failure data obtained from a large FPGA-based design used in the logical unit module board of a commercial information system. This comparison confirms that the projections obtained from our analytical tool are accurate (there is an 81% overlap in FIT rate range obtained with our analytical modeling framework and the field failure data studied).