The National Institute of Standards and Technology Handbook 133, Checking the Net Contents of Packaged Goods, has been prepared as a procedural guide for the compliance testing of net contents statements on packaged goods. Compliance testing of packaged goods is the determination of the conformance results of the packaging, distribution, and retailing process (the packages) to specific legal requirements for net content declarations. This handbook has been developed primarily for the use of government officials; however it should also be useful to commercial and industrial establishments in the areas of packaging, distribution, and sale of commodities. In conducting compliance testing, the conversion of quantity values from one measurement system to another (e.g., from the metric system to the avoirdupois system) should be handled with careful regard to the implied correspondence between accuracy of the data and the number of digits displayed. In all conversion, the number of significant digits retained should ensure that accuracy is neither sacrificed nor exaggerated. For this edition of Handbook 133 all dimensions for test procedures, devices, or environments have been rounded to two significant digits (e.g., 2.5 cm to 1.0 in) or to a precision level applicable to the test equipment (e.g., 200 kPa for 25 psi and 35 MPa for 5000 psi).