Class limits are the smallest and largest observations (data, events etc) in each class.

Therefore, each class has two limits: a lower and upper.

Class Boundaries are the midpoints between the upper-class limit of a class and the lower class limit of the next class in the sequence.

Therefore, each class has an upper and lower class boundary.

Example:

Class             Frequency

100-200           10

For the class, 100 – 200

The lower-class limit is 100

The lower-class boundary is the midpoint between 100 and 200 that is 150