Excel Box and Whisker Plot Examples With Setup Tips

Excel box-and-whisker plot examples include comparing test scores across classes, delivery times across routes, or monthly measurements across groups. In Excel for Microsoft 365 on Windows, arrange each group in its own column, select the data, then choose Insert > Insert Statistic Chart > Box and Whisker.

What a box-and-whisker plot shows

A box plot summarizes how a set of numerical values is distributed. The line inside the box marks the median, or middle value. The bottom and top of the box mark the first and third quartiles, often called Q1 and Q3. Together, those quartiles contain the middle half of the observations. The box’s height is the interquartile range, or IQR: Q3 minus Q1.

The whiskers extend from the box to the smallest and largest values that are not classified as outliers under the chart’s rule. In Excel’s standard box-plot convention, values beyond 1.5 times the IQR below Q1 or above Q3 are shown as outlier points when outliers are displayed. Those points are still part of the data; the chart is flagging their distance from the central range, not proving that they are errors.

Unlike a bar chart, a box plot does not primarily compare totals or averages. It helps show spread, skew, central location, and unusually distant observations. Two groups can have the same median but very different boxes and whiskers.

Example: comparing two groups of measurements

Suppose a teacher wants to compare scores from two classes. Put the heading Class A in A1 and Class B in B1, then enter each student’s score below the appropriate heading. For example, Class A might have the values 10, 12, 13, 14, 15, 16, 18, 20, and 45. Class B might have 11, 12, 14, 15, 16, 17, 18, 19, and 21. Each column represents one group, and each row represents one observation.

For Class A, using inclusive quartiles, the median is 15, Q1 is 13, and Q3 is 18. Its IQR is 5. The upper outlier fence is 25.5, so 45 is beyond that fence and appears as a separate point. The upper whisker reaches 20, the highest value still within the fence; the lower whisker reaches 10. Class B has a tighter range, with no value as distant from its box. The comparison makes the unusually high Class A score visible without letting it stretch the scale of the box itself.

In a real chart, use the full set of observations, not precomputed averages or quartiles. A box plot needs the underlying values to show their distribution. If categories have different sample sizes, that is acceptable, but note the group sizes in a caption or nearby table when the difference matters to interpretation.

How to create the chart in Excel

Place a clear heading above each group of numeric observations. Put each group in a separate column, with the group name in the first row. Keep the observations beneath their heading.
Select the headings and values, such as A1:B10 for two groups. If your columns are far apart, select one range and then use Ctrl-click to add another range on Windows; for nonadjacent selections on Mac, use Command-click.
On the ribbon, choose Insert > Insert Statistic Chart > Box and Whisker. Excel inserts a chart based on the selected data.
Check the category labels and orientation. If Excel has arranged the groups incorrectly, select the chart and use Chart Design > Switch Row/Column. The group names should identify the plotted boxes.
Add a descriptive title and, if needed, axis titles through Chart Design > Add Chart Element. Use wording that identifies the measure and units, such as “Delivery time (minutes) by route.”

In current Excel desktop editions for Mac, a box-and-whisker chart is also available among the statistical charts, though ribbon arrangement and labels can vary slightly by release. If the chart command is unavailable, check that you are using a desktop edition that supports this chart type; the exact chart-editing controls may also differ in Excel for the web.

Reading the box, whiskers, and outliers

Compare medians to see which group has the higher typical middle observation. Compare box heights to assess the spread of the middle half: a taller box means those central values are more dispersed. Longer whiskers indicate a broader range outside the box, subject to the outlier rule. A median that sits noticeably nearer one edge of the box can suggest an uneven distribution, though the plot alone does not explain why the data are skewed.

Consider the full shape rather than ranking groups by one statistic. For instance, a route with a lower median delivery time might still have a longer upper whisker and several high outliers. That can mean most deliveries are quick while a smaller number take much longer. A box plot is useful for spotting this pattern, but it does not show the exact frequency of every value or the sequence in which observations occurred.

Outliers deserve investigation, not automatic deletion. Check whether a point reflects a recording mistake, a different measurement process, or a genuine rare case. If it is valid, retaining it usually gives a more honest picture. A chart can show outliers as individual points, but it does not establish their cause.

Quartile settings and a formula check

Excel’s Format Data Series pane includes a choice between inclusive and exclusive median calculations. The choice can change quartile positions, particularly in small samples, so two otherwise correct box plots may have slightly different boxes. For a consistent comparison, use the same setting for every group and state the method when the result will be reviewed or reproduced.

To check the example values independently, assume Class A’s nine observations are in A2:A10. With the inclusive method, Q1 is 13:

=QUARTILE.INC(A2:A10,1)

With those same values in A2:A10, Q3 is 18:

=QUARTILE.INC(A2:A10,3)

With the same cell layout, the IQR is 5:

=QUARTILE.INC(A2:A10,3)-QUARTILE.INC(A2:A10,1)

These checks use Excel’s QUARTILE.INC function, so choose the chart’s inclusive setting for a like-for-like comparison. They are optional calculations; the chart can be created directly from the raw values.

Formatting choices that improve comparisons

Use a meaningful vertical scale and consistent units across groups. If separate charts use different scales, visual comparisons of spread can be misleading. Order categories logically—for example, by time period, process stage, or a meaningful low-to-high sequence—rather than alphabetically if that obscures the story.

To inspect chart controls, right-click a box and choose Format Data Series. Under Series Options, Excel provides settings such as Show outlier points, Show inner points, Show mean markers, Show mean line, and the quartile calculation. Inner points can reveal the individual observations, but may clutter a chart with large samples. Mean markers can complement the median, while a mean line connects group means; do not confuse either with the median line inside each box.

Keep labels readable and avoid decorative effects that make boxes hard to compare. If there are many categories, enlarge the chart or split it into a small number of related charts with the same scale. Include units and sample sizes where they help readers understand what was measured.

Common problems and how to fix them

The chart shows one box instead of several: Check whether each group occupies its own column or row and whether the headings were included in the selection. Try Chart Design > Switch Row/Column if Excel interpreted the layout the other way around.
A group name appears as a data point: Make sure the heading is in the header row and is recognized as a label. When creating the chart, select the headings together with the numeric data.
The quartiles do not match another tool: Compare the inclusive or exclusive setting and the quartile convention used by the other tool. Small samples are especially likely to show differences.
An apparent outlier is missing: Open Format Data Series and check Show outlier points. Also confirm the value is numeric and that it is beyond the chart’s outlier threshold.
The chart has unexpected gaps or values: Inspect the source range for text stored as numbers, accidental blanks, or stray entries. Keep the data range limited to the intended observations and headings.

When to choose a different chart

A box plot is a strong choice when the question is how distributions differ across groups. A column chart is more suitable when the main goal is to compare a single summary value, such as a total or average, but it hides much of the variation in the underlying observations. A histogram focuses on the frequency pattern within one numeric distribution, while a dot plot can make every observation easier to see for a small sample.

For very small groups, individual values may be more informative than a box alone; showing inner points or using a dot plot can help. For large samples, a box plot offers a compact summary, but a histogram or density-oriented view may better reveal multiple clusters. Choose based on the question, not simply on which chart looks more polished.

Frequently Asked Questions

How do I make a box-and-whisker plot in Excel?
Select the group headings and numeric data, then choose Insert > Insert Statistic Chart > Box and Whisker. Check the group labels, quartile setting, and outlier display before sharing the chart.

What do the dots outside an Excel box plot mean?
They are values Excel classifies as outliers under the box plot’s 1.5-IQR rule when Show outlier points is enabled. They are observations to examine, not necessarily errors or values that should be removed.

Can a box plot compare groups with different numbers of observations?
Yes. Each group can contain a different number of numeric values. For a fair reading, make the sample size clear when it affects how much evidence each box represents.

Why are my box plot quartiles different from another program?
Programs can use different quartile conventions, and Excel lets you choose inclusive or exclusive median calculations. Match the setting and method before comparing the numbers.

Does the line in the box show the average?
No. The line inside the box marks the median. If you enable a mean marker or mean line, Excel displays the average separately.

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

More in How-to basics

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

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