What this calculator does
Class width for a histogram works out how wide each bin should be, from either a target class count or Sturges’ rule. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
Formulawidth = (max − min) / classes; Sturges’ rule: classes ≈ ⌈log₂ n + 1⌉
The inputs explained
| Field | What to enter |
|---|---|
| Minimum value | A number. Starts at 12. |
| Maximum value | A number. Starts at 98. |
| Desired number of classes | A number. Starts at 8. |
| Sample size (for Sturges’ rule) | A number. Starts at 50. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with minimum value
Every other input is held at the calculator’s starting values while minimum value varies. Select any row to load that scenario into the calculator.