Box & Whisker Plot Maker
Paste one or more numerical datasets to create a box plot instantly. Compare distributions, calculate quartiles and IQR, identify outliers, and download the finished chart as a PNG.
Create your box and whisker plot
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1. Enter datasets
Or drop one file here. Up to 2 MB; nothing is uploaded to a server.
Paste named rows (for example: Group A,12,14,18), or spreadsheet columns with dataset names in the first row and values underneath. Commas and tabs work. Check the layout and header setting in the import preview.
Preview
3 valid datasets
Applies to PNG and SVG downloads. Dark labels work best on light backgrounds. The preview checkerboard is not exported.
Applies to PNG and SVG downloads. The preview matches the image proportions; wider images retain side padding to avoid distortion. SVG stays sharp when resized; some editors may substitute fonts.
Calculated statistics
| Dataset | n | Min | Q1 | Median | Mean | Q3 | Max | IQR | Fences | Outliers |
|---|---|---|---|---|---|---|---|---|---|---|
| Group A | 8 | 12 | 14.5 | 18.5 | 19.25 | 22.5 | 31 | 8 | 2.5 to 34.5 | None |
| Group B | 8 | 8 | 12 | 16 | 15.75 | 19.5 | 23 | 7.5 | 0.75 to 30.75 | None |
| Group C | 8 | 4 | 6.5 | 9.5 | 12.125 | 11.5 | 38 | 5 | -1 to 19 | 38 |
For a numerical summary alongside the plot, use the descriptive statistics calculator to review mean, standard deviation, quartiles and potential outliers.
Turn on Show individual points to see observations beside each box. For a text-based view of a small dataset, try a stem-and-leaf plot.
How to make a box and whisker plot
- Enter each dataset. Paste named rows or spreadsheet columns, check the import preview, or edit the dataset cards manually.
- Review the calculations. Check the five-number summary, IQR, fences, and detected outliers below the chart.
- Choose an orientation. Use a vertical layout for familiar classroom plots or horizontal boxes when group names are longer.
- Export the result. Show or hide outlier points, add a useful title and axis label, then download a PNG or vector SVG. SVG keeps shapes and text editable; some graphics editors may substitute fonts.
What does a box and whisker plot show?
A box and whisker plot summarizes the center and spread of numerical data. The box runs from the first quartile (Q1) to the third quartile (Q3), so it contains the middle 50% of the observations. A line inside the box marks the median. The whiskers extend to the most extreme values that are not classified as outliers.
This compact design makes box plots especially useful when you need to compare distributions. You can quickly see which group has a higher typical value, which group varies more, whether the distribution appears uneven, and whether unusual observations sit beyond the whiskers.
The five-number summary
The traditional five-number summary contains the minimum, Q1, median, Q3, and maximum. ChartMaker lists those five values in the accessible statistics table, along with sample size, IQR, fences, and outliers. When outliers exist, the plotted whiskers stop at the smallest and largest non-outlier values rather than at the raw minimum and maximum.
Median, quartiles, and IQR
The median divides sorted data into a lower and upper half. With median-of-halves methods, Q1 is the median of the lower half and Q3 is the median of the upper half. Their difference, Q3 minus Q1, is the interquartile range (IQR). Unlike the full range, the IQR is based on the central half of the observations and is less affected by extremely high or low values.
Quartile conventions differ slightly between textbooks and software. This calculator defaults to the exclusive median-of-halves method: when a dataset has an odd number of observations, the overall median is not included in either half before Q1 and Q3 are calculated. Stating the method matters when comparing results from different tools, especially for small datasets.
Choosing a quartile method
Inclusive median of halves puts the overall median in both halves when the sample size is odd. Linear interpolation uses positions (n − 1) × 0.25 and (n − 1) × 0.75, counting from zero in the sorted values. The latter matches R type 7 and Excel QUARTILE.INC; it is not the same as inclusive median of halves.
For 1, 2, 3, 4, 5, 6, 7, 8, both median-of-halves methods give Q1 = 2.5 and Q3 = 6.5; linear interpolation gives 2.75 and 6.25. A single value is used for all three quartiles. Changing methods also recalculates fences, whiskers, and outlier classifications, so compare groups using the same convention.
The optional diamond marker shows the arithmetic mean, calculated from every valid value including outliers. Hiding outlier points does not remove them from the mean. The line inside the box always represents the median.
How this box plot identifies outliers
The lower fence is Q1 − 1.5 × IQR and the upper fence is Q3 + 1.5 × IQR. Values outside those boundaries are shown as individual points when outliers are enabled. The fences are calculation thresholds; they are not necessarily observed values. The whiskers end at the most extreme actual observations that remain inside the fences.
An outlier is a signal to investigate, not an automatic error. It may represent a valid rare case, a measurement problem, or a subgroup that deserves separate analysis. Keep the original context in mind before removing any value.
Interpreting and comparing box plots
Compare centers
Use median lines to compare the typical value of several groups without assuming a normal distribution.
Compare spread
Wider boxes indicate a larger IQR, while longer whiskers show more variation outside the central 50%.
Notice asymmetry
An off-center median or one long whisker can suggest skew, though the raw data should confirm the pattern.
A box plot summarizes a distribution rather than showing its full shape. The optional individual points show every observation, including outliers, with sideways spreading to separate repeated values. Dense samples can overlap. A histogram is a useful companion for seeing frequency and distribution shape.
Value axis limits and ticks are optional: blank fields use Auto. Custom limits clip the drawing, not the dataset, so quartiles, means and outlier calculations still use all original values. Reset the axis to Auto to show the full automatic range again.
Box plot maker FAQ
How does this box plot maker calculate quartiles?
The default is exclusive median of halves: exclude the overall median when splitting an odd-sized dataset. Customize also offers inclusive median of halves and linear interpolation (R type 7). The selected method is shown with the chart and statistics.
How are outliers identified?
A value is marked as an outlier when it is below Q1 minus 1.5 times the IQR or above Q3 plus 1.5 times the IQR. Whiskers end at the most extreme values inside those fences.
Can I compare multiple datasets?
Yes. Paste named dataset rows, paste spreadsheet columns with dataset names in the header row, or add datasets manually. Check the layout in the import preview. The chart and statistics table display every valid dataset together for comparison.
Does ChartMaker upload my values?
No. Parsing, quartile calculations, chart rendering, and PNG or SVG creation all happen locally in your browser.
Lessons and printable worksheets
Practise with original sample data, worked answers, and free classroom worksheets.