Frequency polygon maker
Paste raw numbers and get a frequency polygon (midpoints of each class joined by straight lines) over its histogram, with the frequency table worked out.
Paste raw numbers — separated by spaces, commas, tabs or new lines. Don’t count them first; the tool does that.
Labels & options
| Bin | Count | Relative |
|---|---|---|
| 210 – <220 | 2 | 5% |
| 220 – <230 | 4 | 10% |
| 230 – <240 | 9 | 22.5% |
| 240 – <250 | 10 | 25% |
| 250 – <260 | 8 | 20% |
| 260 – <270 | 5 | 12.5% |
| 270 – <280 | 2 | 5% |
| Group | n | Min | Q1 | Median | Q3 | Max | Mean | SD |
|---|---|---|---|---|---|---|---|---|
| Data | 40 | 212 | 234.5 | 244.5 | 255 | 276 | 244.7 | 14.81 |
Write a caption for this chart
Get a plain-English summary with the key numbers — handy for slide notes, reports and alt text. Your data is sent to the AI only when you click.
How to make a frequency polygon
- Paste raw values; there’s no need to count them into classes first.
- Leave bins at 0 for automatic class widths, or set your own bin width.
- “Frequency polygon” is ticked: the line joins each class midpoint at its frequency, closing at zero on both ends.
- Download PNG or SVG; the frequency table is under the chart.
Same data, different bin width
30 commute times in minutes. Drag the bin width and watch the shape change — the data never does.
Width 2 shows mostly noise; 25 squashes everything into two bars. Around 5–10 shows the real story: most people commute 20–35 minutes, with a long tail to the right.
How a frequency polygon is drawn
For every class (bin), find the midpoint (lower limit + upper limit) ÷ 2 and plot it at the class frequency. Join the points with straight lines, then add one empty class at each end so the polygon starts and finishes on the x-axis. The area under the polygon equals the area of the histogram bars.
Frequency polygon or histogram?
They carry the same information. Polygons are better for comparing distributions, because two lines can share one chart where two sets of bars would hide each other. Histograms are more familiar for a single data set. Here the polygon is drawn over the histogram so you can see how one becomes the other; see the histogram maker for more on choosing bins.
Questions
How do you make a frequency polygon?
Group the data into classes, find each class midpoint, plot midpoint against frequency, join the points with straight lines and close the shape at zero one class-width beyond each end. Pasting raw data here does all of that.
What is the difference between a histogram and a frequency polygon?
A histogram shows each class as a bar; a frequency polygon joins the class midpoints with lines. Both show the same distribution.
How do you find the midpoint of a class?
Add the lower and upper class limits and divide by two. For the class 230–240, the midpoint is 235.
Why does a frequency polygon touch the x-axis?
An empty class is added at each end so the line closes at zero frequency, which keeps the area under the polygon equal to the histogram’s.