What is the difference between a limit and a tolerance?

• A. Limits define the accepted high and low sizes; tolerance is the total permissible variation between them.
• B. Tolerance defines the accepted high and low sizes; limits are the total variation.
• C. Limit and tolerance are interchangeable terms.
• D. Tolerance is a single fixed size.

Answer: (A)

Limits are the extreme acceptable sizes a part can have, defined as an upper limit and a lower limit. Tolerance is the amount of variation allowed between those extremes. For example, if a part must measure between 9.990 and 10.010, the lower and upper limits are 9.990 and 10.010, and the tolerance is 0.020. This reflects how much a dimension can vary from nominal while still being acceptable, often written as a plus/minus range around a nominal size.

This makes the chosen statement correct because it exactly captures that relationship: limits set the accepted high and low sizes, and tolerance is the total permissible variation between them. Other choices mix up the concepts or treat them as interchangeable or as a single fixed size, which isn’t how they work in practice.