The WIM System Calibration tool is used for WIM system calibration or validation by collecting test truck data, evaluating WIM measurement accuracy and consistency, determining if the results meet WIM data measurement error tolerances, and computing WIM calibration factors. This tool is based on the procedures specified in current WIM specifications including ASTM E1318-09, LTPP Calibration Protocol, FHWA WIM Pocket Guide for Calibration and Maintenance, and ADOT WIM Calibration Tool. This tool determines if WIM measurement errors based on calibration test truck runs meet ASTM E1318-09 error tolerances for selected ASTM WIM system Types (I, II, or III) using ASTM E1318-09 or LTPP WIM system performance requirements. The tool is designed to be used in the field and provided as a downloadable Windows-based application.