![General drawing tolerances General drawing tolerances](https://www.lynkoa.com/sites/default/files/questions/answer/20/05/2014/iso13920.jpg)
International Tolerance (IT) Grades Table ChartInternational Tolerance (IT) Grades table reference ISO 286. This mechanical tolerance grade specifies tolerances with associated manufacturing processes for a given dimension.International Tolerance grades are calculated as following:Where:T = Tolerance in micrometers µmD = Geometric mean dimension in millimeters mmITG = IT Grade, a positive integer.Application:Most manufacturing processes have an IT Grade designated for specification. IT grades provide guidance for typical manufacturing process capability or how precise one can except manufacture of a particular features or features.When designing a part and specifying mechanical tolerances, engineering or design will determine size and location for a particular feature. Using the designated International Tolerance Grade formula, the IT Grade required or typical to produce the part feature is assigned.
![Tolerance Tolerance](/uploads/1/2/5/5/125556965/833962494.jpg)
Tol′er.a`tor, n.
ISO Tolerances. Nominal Dimension, Tolerance Zone in mm (External Measurements). Over, to, m6, h6, h8, h10, h11, h13, h14, h15, h16. 0, 1, +0.002 +0.008.