How do I find the interval for a frequency table

First you need to know how to calculate the class interval;

Calculating the class interval using the following formula:

Class interval = range : number of classes. If you have 15 classes of income in the distribution of income example, work out 30 : 15 = $2 billion.

Anyways, back to your question how you would find the interval for a frequency table is yeah think I explained it right.