Box Plot Maker (Box and Whisker Plot)
Draw a box plot from your data, with the five-number summary and outliers.
How to make a box plot
Enter one group of numbers per line. You can start a line with a name and a colon, such as Class A: 55 62 68 70, and up to 8 groups are drawn side by side. Each group needs at least 4 values. The tool draws the boxes and gives a five-number summary for each group.
How to read a box plot
- The box runs from the first quartile (Q1) to the third quartile (Q3), so it holds the middle 50% of the data.
- The line inside the box is the median.
- The whiskers extend to the lowest and highest values that are within 1.5 × IQR of the box.
- Dots beyond the whiskers are outliers.
Worked example
Three classes are compared. Class A has a median of 78 and a spread (IQR) of 17.5. Class B has a median of 72 and a narrower IQR of 10, with one outlier: a score of 99, far above the rest. Class C has a median of 68 and the widest spread (IQR 21). The plot shows at a glance that Class A scores highest in the middle, Class B is the most consistent, and Class C varies the most.
Every chart has Download PNG and Download SVG buttons under it, so you can save the image for a report, an essay or a slide. Charts follow your light or dark theme on the page, and the saved image keeps its colours.
How the quartiles are found
The tool uses the median-of-halves method: Q1 is the median of the lower half of the sorted data and Q3 is the median of the upper half, leaving out the middle value when the count is odd. Other software, such as Excel or R, may use slightly different methods, so small differences in Q1 and Q3 are normal. The outlier rule is: a value is an outlier if it is below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR.
Box plots are good for comparing groups. To see the full shape of one set of data, use the histogram maker.
How to cite this page
CalcPulse. (2026). Box Plot Maker. https://calcpulse.com/box-plot-maker/
Frequently asked questions
What is a box plot?
A chart that shows the median, quartiles and range of a data set, plus any outliers, in one picture.
How do I read the box and whiskers?
The box covers the middle 50% of the data, the line is the median, and the whiskers reach the furthest values that are not outliers.
What counts as an outlier?
A value more than 1.5 times the interquartile range below Q1 or above Q3.
Can I compare several groups?
Yes. Enter each group on its own line, and the boxes are drawn side by side on the same scale.
Why do other tools give slightly different quartiles?
There are several accepted methods for calculating quartiles. This tool uses the median of each half.
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