Iris sepal length by species
Compare sepal lengths across three iris species (150 samples).
Histogram Maker
FigranA histogram maker for raw observations or frequency tables, with shared bin boundaries for comparing groups.
- Compare groups or enter a frequency table
- Review exact bin boundaries
- Free SVG and 300 DPI PNG
Bins table
| Lower | Upper | setosa | versicolor | virginica | Total frequency | Total relative frequency | Total density | Closure |
|---|---|---|---|---|---|---|---|---|
| 4 | 4.5 | 4 | 0 | 0 | 4 | 0.0267 | 0.0533 | [left,right) |
| 4.5 | 5 | 16 | 1 | 1 | 18 | 0.12 | 0.24 | [left,right) |
| 5 | 5.5 | 25 | 5 | 0 | 30 | 0.2 | 0.4 | [left,right) |
| 5.5 | 6 | 5 | 20 | 6 | 31 | 0.207 | 0.413 | [left,right) |
| 6 | 6.5 | 0 | 15 | 17 | 32 | 0.213 | 0.427 | [left,right) |
| 6.5 | 7 | 0 | 8 | 14 | 22 | 0.147 | 0.293 | [left,right) |
| 7 | 7.5 | 0 | 1 | 6 | 7 | 0.0467 | 0.0933 | [left,right) |
| 7.5 | 8 | 0 | 0 | 6 | 6 | 0.04 | 0.08 | [left,right] |
Summary statistics
| Statistic | setosa | versicolor | virginica |
|---|---|---|---|
| n | 50 | 50 | 50 |
| Mean | 5.01 | 5.94 | 6.59 |
| Median | 5 | 5.9 | 6.5 |
| SD (sample) | 0.352 | 0.516 | 0.636 |
| Min | 4.3 | 4.9 | 4.9 |
| Max | 5.8 | 7 | 7.9 |
| Skewness (G1) | 0.12 | 0.105 | 0.118 |
| Excess kurtosis (G2) | -0.253 | -0.533 | 0.0329 |
Histogram examples: real data and frequency tables
Old Faithful eruption duration
See two clusters in 272 Old Faithful eruption durations.
New York ozone readings (complete cases)
Explore 116 non-missing New York ozone readings.
Old Faithful frequency table
Inspect 272 eruptions in one-minute frequency intervals.
Black cherry tree volume
Compare 31 black cherry trees using unequal-width bins.
How to make a histogram
1Enter your data
Paste numeric columns or upload a file. To make a histogram from a frequency table, switch to Frequency table and supply contiguous lower, upper and count columns, including zero-count intervals.
2Choose bin boundaries
For a frequency histogram, choose a bin rule or Custom edges, then review the counts. Use the same boundaries when comparing groups.
3Download your histogram
Save an SVG or 300 DPI PNG, and export the bins as CSV.
How to read a histogram: choosing the number of bins
The same 272 Old Faithful eruptions, shown from 1 to 6 minutes with different bin counts. Each plot uses its own frequency scale.
Sturges (automatic)
Sturges gives a starting count; boundaries are rounded to convenient values.
Freedman–Diaconis (5 bins)
The interquartile-range rule suggests five bins for these data.
Too few bins (2)
Two wide bins can conceal detail within each group of observations.
Too many bins (25)
Narrow bins can emphasize small fluctuations as well as structure.
Adjacent bars represent numerical intervals. Choose Relative frequency under Bar height to make a relative frequency histogram: heights show proportions rather than counts. For unequal widths, choose Density so each bar’s area equals its relative frequency.
Data source: Old Faithful (R datasets).
Histogram FAQ
Can I make a histogram with categorical data?
No. A histogram groups numerical observations into adjacent intervals; use a bar chart to compare categories.
Can this histogram graph maker use a frequency table?
Yes. Enter contiguous lower, upper and count columns, including zero-count intervals.
How should I choose bins?
Freedman–Diaconis is a starting point. Compare bin counts, widths or explicit edges appropriate to your data and report the boundaries.
Can I set class boundaries in the histogram maker?
Yes. Choose Custom edges under Bin boundaries. Bins include the left edge and exclude the right edge, except the last bin includes both edges.
How are missing values handled?
In group columns, blank cells are skipped. In single-column data, empty or invalid cells are reported.
How do I make a density histogram for unequal bin widths?
Choose Density under Bar height. Density is count divided by total count and bin width; the area of each bar is its relative frequency.
What can I download?
Download an editable SVG, a 300 DPI PNG, or a CSV with exact bin boundaries, counts, proportions, density and closure.
Is my data uploaded?
The histogram is calculated in your browser. A draft may be saved locally on this device.
What should a histogram figure caption include?
Name the variable and units, give the sample size and bin boundaries or bin-selection rule, and say whether bar height shows counts, relative frequency or density. Identify the groups and any fitted normal curve.
Make your histogram
Enter your data, review the bins, and download your histogram.