In statistics, **class size** refers to the difference between the upper and lower boundaries of a class in a frequency distribution.

The following examples shows how to find the class size for various frequency distributions.

**Example 1: Finding Class Size for Basketball Data**

Suppose we have the following frequency distribution that describes the number of points scored by various basketball players in a league:

The first class has a lower limit of 1 and an upper limit of 5. Thus, the class size would be calculated as:

- Class size: 5 – 1 =
**4**

The second class has a lower limit of 6 and an upper limit of 10. Thus, the class size would be calculated as:

- Class size: 10 – 6 =
**4**

No matter which class we analyze in the frequency distribution, we’ll find that the class size is **4**.

**Example 2: Finding Class Size for Sales Data**

Suppose we have the following frequency distribution that describes the number of widgets sold by a certain company on different days:

The first class has a lower limit of 1 and an upper limit of 10. Thus, the class size would be calculated as:

- Class size: 10 – 1 =
**9**

The second class has a lower limit of 11 and an upper limit of 20. Thus, the class size would be calculated as:

- Class size: 20 – 11 =
**9**

No matter which class we analyze in the frequency distribution, we’ll find that the class size is **9**.

**Additional Resources**

How to Find Class Boundaries (With Examples)

How to Find Class Intervals (With Examples)

How to Find Class Limits (With Examples)