Frequency Distribution Calculator
Paste raw data to generate class intervals, frequencies, and relative frequencies suitable for grouped tables and histograms.
Count: 13
Classes used: 4
| Class Interval | Frequency | Relative Frequency | Cumulative Frequency |
|---|---|---|---|
| [12.00, 19.00) | 3 | 0.231 | 3 |
| [19.00, 26.00) | 4 | 0.308 | 7 |
| [26.00, 33.00) | 3 | 0.231 | 10 |
| [33.00, 40.00] | 3 | 0.231 | 13 |
How to Use This Calculator
- Paste numerical observations (each value once per occurrence).
- Optionally set the number of classes; otherwise, √n is used.
- Review class intervals, frequencies, and cumulative counts.
- Export the table to create histograms or grouped frequency charts.
Formula
Class width ≈ (max − min) / k (rounded to convenient value)
Relative frequency = class frequency / total observations
Cumulative frequency = sum of class frequencies up to that class
Choose equal-width classes unless specific analytical needs dictate otherwise.
Frequently Asked Questions
How do I select the number of classes?
Use the square-root rule (√n) or Sturges’ rule (1 + 3.3 log₁₀ n) as starting points.
Can classes have unequal widths?
Yes, but equal widths simplify interpretation and histogram construction.
What about decimal endpoints?
Round boundaries to readable values (e.g., nearest 1 or 5) to ease reporting.