Box and whisker plot maker
Paste one or more columns of numbers. You get the box plot plus the five-number summary, mean, standard deviation and any outliers — ready to copy into homework or a report.
One column per group with a header row (paste from a spreadsheet), or just a list of numbers for one box.
Labels & options
| Group | n | Min | Q1 | Median | Q3 | Max | Mean | SD |
|---|---|---|---|---|---|---|---|---|
| Courier A | 10 | 2 | 3 | 4.5 | 6 | 12 | 5.1 | 2.85 |
| Courier B | 10 | 3 | 4 | 5.5 | 7 | 9 | 5.7 | 1.89 |
| Courier C | 10 | 1 | 2 | 3 | 4 | 9 | 3.6 | 2.22 |
Quartiles use the median-excluded method (as on TI-84 calculators). Outliers lie beyond 1.5 × IQR from the box: Courier A: 12 · Courier B: none · Courier C: 9.
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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 box and whisker plot
- Paste your numbers. For several groups, paste columns with a header row (e.g. Courier A, Courier B).
- Read the summary table: min, Q1, median, Q3, max, mean and SD for every group.
- Outliers (beyond 1.5 × IQR) are drawn as open circles.
- Switch to horizontal if you prefer, then download.
When does a value become an outlier?
Ten delivery times in days. Drag the slowest one further out. It turns into a separate dot once it passes Q3 + 1.5 × IQR.
Q1 5 · median 7 · Q3 9 · IQR 4
Upper fence = Q3 + 1.5 × IQR = 9 + 1.5 × 4 = 15. 12 is inside, so the whisker reaches it.
How to read a box plot
The box spans the middle half of the data, from the first quartile (Q1) to the third (Q3); that width is the interquartile range (IQR). The thick line inside is the median. Whiskers reach to the smallest and largest values that aren’t outliers, and points more than 1.5 × IQR beyond the box are plotted separately — the convention introduced by John Tukey.
How the quartiles are calculated
Sort the data and find the median. Q1 is the median of the lower half and Q3 the median of the upper half, excluding the overall median when n is odd. This matches TI-83/84 calculators and most school courses. Excel’s QUARTILE.INC and some software use interpolation, so their quartiles can differ slightly on small data sets.
Questions
What is the five-number summary?
Minimum, first quartile (Q1), median, third quartile (Q3) and maximum. The table under the chart lists them for every group.
How are outliers found?
Any value below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR is flagged as an outlier and drawn as a circle. The whisker stops at the most extreme non-outlier.
Why is my Q1 different from Excel?
Excel’s QUARTILE.INC interpolates between values. This tool uses the median-of-halves method taught in schools and used on TI calculators. Both are legitimate; the difference shrinks with more data.
Can I compare several groups?
Yes. Paste each group as a column with a header row. The boxes share one axis so you can compare them directly.