United States Military Standard

A United States Defense Standard, often called a military standard, “MIL-STD”, “MIL-SPEC”, or (informally) “MilSpecs”, is used to help achieve standardization objectives by the U.S. Department of Defense.

Standardization is beneficial in achieving interoperability, ensuring products meet certain requirements, commonality, reliability, total cost of ownership, compatibility with logistics systems, and similar defense-related objectives.

Defense Standards are also used by other non-Defense government organizations, technical organizations, and industry. This article discusses definitions, history, and usage of Defense Standards. Related documents, such as Defense Handbooks and Defense Specifications are also addressed.


Defense standards evolved from the need to ensure proper performance and maintainability of military equipment. For example, due to differences in dimensional tolerances, in World War II American screws and bolts did not fit British equipment properly and were not fully interchangeable. Defense standards provide many benefits, such as minimizing the number of types of ammunition, ensuring compatibility of tools, and ensuring quality during production of military equipment. This results, for example, in ammunition cases that can be opened without tools. The proliferation of standards had drawbacks, however. It was argued that the large number of standards, nearly 30,000 by 1990, imposed unnecessary restrictions, increased cost to contractors, and hence the DOD, and impeded the incorporation of the latest technology.

Responding to increasing criticism, Secretary of Defense William Perry issued a memorandum in 1994 that prohibited the use of most defense standards without a waiver. This has become known as the “Perry memo”. Many defense standards were canceled. In their place, the DOD encouraged the use of industry standards, such as ISO 9000 series for quality assurance. Weapon systems were required to use “performance specifications” that described the desired features of the weapon, as opposed to requiring a large number of defense standards. In 2005 DOD issued a new memorandum which eliminated the requirement to obtain a waiver in order to use defense standards. The 2005 memo did not reinstate any canceled defense standards.

According to a 2003 issue of Gateway, published by the Human Systems Information Analysis Center, the number of defense standards and specifications have been reduced from 45,500 to 28,300. However, other sources noted that the number of standards just before the Perry memorandum was issued was less than 30,000, and that thousands have been canceled since then. This may be due to differences in what is counted as a “military standard”.



Click here to view United States Military Specifications