How to Calculate Histogram
What is Histogram?
A histogram displays the frequency distribution of a dataset by dividing the range into equal-width bins and counting how many values fall in each bin. It reveals the shape, spread, and central tendency of data.
Formula
Bins: define intervals. Frequency: count of values in each bin. Density = Frequency / (Bin Width × Total Count)
- Bin width
- size of each interval
- Frequency
- count of data points in bin
- Density
- normalized frequency (probability per unit width)
Step-by-Step Guide
- 1Choose number of bins (Sturges: 1+log₂n)
- 2Bin width = (max−min)/bins
- 3Count values in each bin
- 4Bar height = frequency (or relative frequency)
Worked Examples
Input
20 test scores, 5 bins
Result
Each bin spans 10 points; reveals normal-like distribution
Frequently Asked Questions
How many bins should a histogram have?
Use Sturges' rule (k ≈ 1 + log₂(n)) or √n. Too few bins hide details; too many create noise.
Is a histogram the same as a bar chart?
No. Histograms show continuous data with adjacent bins; bar charts show categorical data with gaps.
What does the area of a histogram bar represent?
The area represents relative frequency (or probability if normalized).
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