ASTM D7438-13 is a standard practice developed by the American Society for Testing and Materials (ASTM) for the measurement of the water content of solid wood and its articles (including wood articles containing additives) with a handheld moisture meter under end-use conditions. The standard specifies field calibration methods, usage guidelines, and data interpretation for handheld moisture meters, with the aim of improving the accuracy and Reliability of measurements. The standard also addresses the effect of wood properties (e.g., texture, growth ring orientation) on measurement results and provides detailed steps for relevant calibrating and application.