Geometric Dimensioning & Tolerancing (GD&T)

The language of engineering design. Learn how to communicate intent clearly and ensure functionality.

VIDEO SOURCEContent courtesy of:R. Dean Odell

Why GD&T Matters

Geometric Dimensioning and Tolerancing (GD&T) is a system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and computer-generated three-dimensional solid models that explicitly describes nominal geometry and its allowable variation.

  • Ensures FunctionalityGuarantees that parts will fit and function at the assembly level.
  • Reduces CostAllows for maximum tolerance zones (bonus tolerances) where possible, reducing manufacturing scrap.
  • Eliminates AmbiguityProvides a single, clear interpretation of design intent, unlike traditional +/- tolerancing.