Side-by-Side Box Plot in Excel: Create and Compare Data

To create a side-by-side box plot in Excel for Microsoft 365 on Windows, arrange each group’s numeric observations in a separate column, select the data, then choose Insert > Insert Statistic Chart > Box and Whisker. Excel draws a box for each column so you can compare medians, spread, and potential outliers across groups.

What a side-by-side box plot shows

A box plot, also called a box-and-whisker plot, summarizes the distribution of numeric data. Each box represents the middle half of a group’s values: its lower edge is the first quartile, or Q1, and its upper edge is the third quartile, or Q3. The line inside the box marks the median. The distance between Q1 and Q3 is the interquartile range (IQR), a measure of the middle spread.

Whiskers extend to values that are not classified as outliers. In Excel’s box-and-whisker chart, values beyond the usual 1.5-times-IQR limits can appear as individual outlier points. This makes it easier to see whether one group has a higher typical value, more variation, or unusually distant observations. A box plot is a summary, not a replacement for the underlying data: it does not show every value unless you enable the inner-points option.

For example, comparing delivery times for three shipping services may reveal that one service has the lowest median but a long upper whisker, meaning its typical delivery is quick while some deliveries take much longer. Putting the three distributions next to one another makes that pattern easier to spot than comparing separate charts.

Arrange the source data for comparison

Use one column per group, with a descriptive header in the first row and numeric observations below it. The groups do not need to contain the same number of observations; leave unused cells blank rather than filling them with zero, because zero is a real value and can change the distribution. Keep the measurement units consistent across columns.

Column A: Service A delivery time in days.
Column B: Service B delivery time in days.
Column C: Service C delivery time in days.

Use a row for each observation where practical. Avoid including totals, averages, explanatory notes, or text in the numeric data area. If your source table has one column for group names and another for measurements, such as Service A and 3.2, first reshape or summarize it so the measurements for each group occupy separate columns. A box plot needs the individual observations to calculate the distribution; a list of precomputed averages alone cannot provide the same information.

When the chart is created, Excel may interpret the selected rows and columns differently than expected. Clear headers help it identify the series. If the plotted boxes appear in the wrong arrangement, select the chart and use Chart Design > Switch Row/Column. The result depends on the source layout, so check the labels and confirm that each box represents the intended group.

Create the chart in Excel for Microsoft 365

Place the group names in the header row and the measurements beneath them.
Select the full range, including the headers and numeric values. For example, if three groups occupy columns A through C with headers in row 1 and observations in rows 2 through 25, select A1:C25.
Choose Insert > Insert Statistic Chart > Box and Whisker on the ribbon.
Check that the chart displays one box for each group and that the horizontal labels match the column headers.
Give the chart a useful title, such as Delivery time by service, and add axis titles if the units might not be obvious.

The chart is linked to its source cells, so editing an observation generally updates the plotted distribution. If you add more observations outside the selected range, however, they may not be included automatically. To include them, adjust the chart’s source data through Chart Design > Select Data, or make the source range an Excel table before building the chart so the range can expand as rows are added.

Format quartiles, whiskers, and points

To change how a box plot is displayed, right-click a box and choose Format Data Series. In the formatting pane, open Series Options. Depending on the selected series and Excel build, the available options include quartile calculation, showing outlier points, showing inner points, showing a mean marker, and showing a mean line. These settings affect what the chart displays; they do not change the raw values in the worksheet.

The quartile calculation setting offers inclusive and exclusive median methods. These approaches can produce different quartile boundaries, especially in small samples, so two charts based on the same values may not have identical box edges if they use different methods. Choose a method that suits your reporting convention, and use it consistently when comparing charts. If the chart is for a formal report, state the method in a note when readers may need to reproduce the calculation.

Use outlier points when you want unusually distant observations to be visible. Turn on inner points when showing the individual measurements would help readers understand sample size or clustering. With many observations, those points can overlap and make the chart crowded. Mean markers and mean lines add another summary, but the median is often more resistant to extreme values. Use consistent colors and scales across related charts; changing colors alone does not make a group statistically different.

How to read and compare the boxes

Start with the median lines to compare typical values, then examine box heights and whiskers to compare variability. A taller box means the middle half of that group’s observations covers a wider range. Long whiskers indicate that values outside the middle half extend farther, while isolated points can flag observations that deserve investigation. These are descriptive clues, not proof of a cause or a statistical significance test.

Suppose the median times for three services are close, but Service C has a much taller box and several high outlier points. The groups may have similar typical delivery times while Service C is less consistent and occasionally much slower. If one box is completely above another, that can suggest a difference in distributions, but it does not by itself establish that the difference is statistically meaningful. Sample sizes, data collection, and the question being asked still matter.

Keep the vertical axis on the same scale when comparing separate charts. A cropped or independently scaled axis can make small differences look dramatic. Also check whether a few unusual values stretch the scale enough to compress the boxes; showing outliers separately does not remove their influence on the chart’s axis range.

Why charts may differ from other quartile calculations

A frequent source of confusion is that quartiles are not calculated in exactly one universal way. Excel’s box plot has an inclusive or exclusive median option, while worksheet functions and other software may use different conventions or interpolation rules. With larger datasets the differences may be small, but with a short list they can noticeably change the box. If you are matching a published result or another tool, verify its quartile convention rather than assuming the chart is wrong.

Another misconception is that every whisker always reaches the minimum and maximum. In a box-and-whisker chart, points beyond the outlier thresholds may be plotted separately, and the whiskers stop at the most extreme non-outlier values. The exact appearance depends on the data and the selected chart options. A chart with no visible outlier dots does not necessarily mean that the data has no unusual values; the points might be turned off or hidden by overlap.

Common problems and fixes

Excel shows one box or the wrong grouping: Confirm that each group has its own numeric column and a header. Try Chart Design > Switch Row/Column, then verify the labels.
A group appears to have a value of zero: Check for zeros entered as placeholders. Replace missing observations with blank cells, not zero, unless zero is genuinely measured.
Text appears in the plotted data: Remove notes or labels from the measurement range. Keep descriptions in headers or outside the selected range.
The chart looks crowded: Widen the chart, shorten category names, or turn off inner points. If there are many groups, split them into focused charts while keeping comparable axis scales.
New rows do not appear: Update the chart’s source range in Chart Design > Select Data, or build the chart from an Excel table and confirm the new rows belong to that table.
The boxes differ from a reference chart: Check the quartile calculation setting, data selection, and outlier display options before comparing the results.

When to use another chart

A box plot is useful when the distribution and spread matter more than showing every observation. For only a few measurements, a dot plot or scatter chart may communicate the actual values more clearly. For a very large dataset, a box plot provides a compact summary, but inner points can become unreadable. A histogram is better when you want to inspect the shape of one distribution, such as whether it has one peak or two; a box plot compresses that shape into quartiles and whiskers.

Excel’s built-in Box and Whisker chart is usually the simplest choice for side-by-side comparisons. A manually constructed chart can offer more control over styling or a specific quartile convention, but it requires calculating the statistics and building the visual elements yourself. For a general comparison in Microsoft 365, start with the built-in chart and move to a custom approach only if its options do not meet your reporting requirements.

Frequently Asked Questions

Can I make a side-by-side box plot with different sample sizes?

Yes. Put each group in its own column and leave unused cells blank beneath shorter groups. Do not add zeros to make the columns equal length unless those zeros are actual observations.

Where is the Box and Whisker chart in Excel?

In Excel for Microsoft 365 on Windows, select the data and choose Insert > Insert Statistic Chart > Box and Whisker. The exact ribbon layout can vary slightly with window size and updates, but the chart is in the Insert tab’s statistical chart options.

Can Excel show the mean as well as the median?

Yes. Right-click a box, choose Format Data Series, and look under Series Options for the mean marker and mean line settings. The median remains the line inside the box; the mean is a separate summary.

Does the whisker show the minimum and maximum?

Not necessarily. Excel can display values beyond the usual 1.5-times-IQR limits as separate outlier points, while the whiskers extend to the most extreme non-outlier values. Turn on outlier points if you want those observations visible.

Can I create this chart in Excel for Mac or Excel for the web?

Box-and-whisker chart availability and ribbon placement can vary by Excel version and platform. In Excel for Mac, look on the Insert tab for the statistical chart option; in Excel for the web, check the Insert chart choices available in your account. If Box and Whisker is not offered, use desktop Excel for Microsoft 365 or create a compatible chart by another method.

Try it: the Date Difference Calculator: days, months, years and weekdays between two dates, with the DATEDIF formulas.

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Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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