ISO tolerantsisüsteemis on 20 tolerantsijärku, mida tähistatakse tähisega IT (International Tolerance) koos järgneva numbriga IT01, IT1, IT2, ... IT18, ning seda tolerantsi suurenemise (täpsuse kahanemise) järjekorras.
In the ISO code system for tolerances on linear sizes, the standard tolerance grade identifier consists of IT followed by a number (e.g. IT7). A specific tolerance grade is considered as corresponding to the same level of accuracy for all nominal sizes.
