What is ASME Y14.5?

  ASME Y14.5 is the standard published by the American Society of Mechanical Engineers (ASME) that establishes the rules, symbols, definitions, and practices for geometric dimensioning and tolerancing (GD&T) on engineering drawings and model-based definitions.

  The standard traces its roots to the US military drawing standard MIL-STD-8, published in 1949 — making structured GD&T a distinctly American engineering innovation that was later adopted globally. The 1982 edition established modern GD&T practice; subsequent editions in 1994, 2009, and 2018 refined and extended it. The current edition is ASME Y14.5-2018, reaffirmed in 2024 (designated ASME Y14.5-2018 R202