Statistics & Probability

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Class Width Calculator.

Calculate a frequency-distribution class width from range and class count.

On-device calculationNo signup
01

Set your values

Results update as you type.

range: 90

range

90.000000
classWidth: 18

classWidth

18.000000
roundedClassWidth: 18

roundedClassWidth

18.000000

Results update automatically as you type.

Use Cases

Creating frequency distributions

Use the calculator to determine the interval size when grouping continuous data into classes for a frequency table or histogram.

Example: For data ranging from 10 to 50 with 5 classes, class width is (50-10)/5 = 8.

Educational statistics exercises

Students and teachers can quickly verify class width calculations for homework or exam preparation.

Example: Check that a dataset with min=0, max=100, and 10 classes yields a class width of 10.

Frequently Asked Questions

What is class width?
Class width is the difference between the upper and lower boundaries of a class in a frequency distribution. It is calculated by dividing the range (maximum minus minimum) by the number of classes.
How do I use the class width calculator?
Enter the minimum value, maximum value, and the number of classes you want. The calculator will compute the class width by subtracting the minimum from the maximum and dividing by the number of classes.
Why is class width important in statistics?
Class width determines the size of intervals in a frequency distribution, affecting how data is grouped and visualized. Choosing an appropriate class width helps in creating clear and meaningful histograms and frequency tables.

Tips & Common Mistakes

Tips

  • Ensure the minimum and maximum values are accurate to get a correct class width.
  • Choose a number of classes that makes sense for your data size; too few or too many can obscure patterns.
  • Round the class width up to a convenient number if you need whole-number intervals.
  • Use the calculated class width to set consistent bin boundaries in your histogram.

Common Mistakes to Avoid

  • Using the number of data points instead of the number of classes in the calculation.
  • Forgetting to subtract the minimum from the maximum before dividing.
  • Not rounding the class width appropriately, leading to awkward interval boundaries.

Last updated: August 13, 2026