How is tolerance calculated?

• A. Tolerance = Upper Limit + Lower Limit
• B. Tolerance = Upper Limit - Lower Limit
• C. Tolerance = Upper Limit x Lower Limit
• D. Tolerance = Upper Limit / Lower Limit

Answer: (B)

Tolerance is calculated as the difference between the upper limit and the lower limit. This value represents the permissible variation in a manufacturing dimension or feature, establishing the acceptable range for that dimension.

For instance, if a part has a specified dimension with an upper limit of 10.0 mm and a lower limit of 9.5 mm, the tolerance is calculated by subtracting the lower limit from the upper limit:

Tolerance = 10.0 mm - 9.5 mm = 0.5 mm.

This means that the actual dimension can vary within that range, up to 0.5 mm. Calculating tolerance this way ensures that parts can be produced with acceptable variations, thereby maintaining function and fit during assembly.

In contrast, multiplying or dividing the upper and lower limits, as found in the other options, does not yield meaningful information regarding permissible deviations in those dimensions and does not conform to standard practices in dimensional tolerancing. Similarly, adding the limits does not provide a true representation of the allowable deviation in size.