Question

IS specifies which of the following total number of grades of tolerances?

• A. 18
• B. 16
• C. 20
• D. 22

Hint:

Remember: The IS system defines 18 tolerance grades — from IT01 to IT16, including IT0 and IT01.

Answer 1

The Correct Option is A

The Indian Standard (IS) system of limits and fits specifies a total of 18 grades of tolerances, known as IT grades (International Tolerance grades).
These are denoted as IT01, IT0, IT1, up to IT16.
Each IT grade defines a tolerance level for the allowable variation in manufactured parts.
- IT01, IT0, and IT1–IT16 form the complete set of 18 grades.
- Lower IT numbers (like IT1 or IT2) represent tighter tolerances.
- Higher IT numbers (like IT14 or IT16) represent looser tolerances.
These grades are used to control dimensional accuracy in engineering components.