Class Width Calculator

What Is Class Width?

Class width is the size of each equal interval when you divide a dataset into groups for a histogram or frequency distribution. It tells you how wide each bin is along the number line, assuming all classes share the same width.

Class Width Formula

The standard formula for class width is:

$$\text{Class Width} = \frac{\text{Maximum} - \text{Minimum}}{\text{Number of Classes}}$$

The difference between maximum and minimum is called the range. Dividing the range by the number of classes gives you a uniform bin size suitable for histograms and frequency tables.

How to Use This Calculator

• Enter the minimum value of your dataset.
• Enter the maximum value of your dataset.
• Specify how many classes (bins) you want.
• The calculator returns the class width and a full table of class intervals with lower and upper limits.

Example

Test scores range from 45 to 90 across 15 students. With 9 classes, the range is $90 - 45 = 45$, so the class width is $45 / 9 = 5$. Each interval spans 5 points: 45-50, 50-55, and so on.

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