This is a general standard specifying the methods for determining the thickness of aluminum and aluminum alloy foils. It details three core methods: calculating thickness by measuring the mass and area of the sample (mass method), direct measurement using a micrometer, and non-destructive measurement using an eddy current thickness gauge. The standard clarifies the applicable scenarios for different methods and specifies sample preparation requirements, measurement procedures, result calculation, and reporting formats. Key instruments required to implement this standard include an analytical balance with an accuracy of 0.1 mg (for the mass method), a micrometer meeting precision requirements, and a calibrated eddy current thickness gauge. This method provides a unified basis for the accurate determination and quality control of aluminum foil thickness.