The operating distance is a critical parameter for evaluating the performance of infrared thermal imaging cameras, influenced by factors such as atmospheric transmission characteristics, target radiation characteristics, detector performance and optical system design. Given the highly complex and variable environmental optical radiation characteristics across diverse meteorological conditions, a method for calculating operating range under different weather conditions is proposed. A calculation formula model is derived through formula derivation, enabling the calculation of operating range under varying meteorological conditions via table lookup and interpolation techniques. This approach simplifies the process and allows measured data to be converted and extrapolated, thereby providing significant assistance in verifying compliance with performance criteria.