What Is a Box and Whisker Plot?
A box and whisker plot (also written as “boxplot” or simply “box plot”) is a compact chart that shows how a set of numbers is distributed. Instead of plotting every value, it summarizes an entire dataset with five numbers: the minimum, the first quartile (Q1), the median, the third quartile (Q3), and the maximum — the so-called five-number summary.
The “box” stretches from Q1 to Q3 and covers the middle 50% of your data, with a line inside marking the median. The “whiskers” extend from the box to the smallest and largest values that are not outliers, and any unusually extreme values are drawn as individual points beyond the whiskers.
Because a box plot shows the center, spread, skewness, and outliers of a dataset at a glance, it is one of the most common charts in statistics classes, scientific papers, and data analysis. This box and whisker plot maker draws the chart for you and calculates every statistic behind it — no formulas required.
How to Use This Box Plot Maker
- Enter your numbers. Type or paste your dataset into the input box above. Values can be separated by commas, spaces, or line breaks — perfect for pasting straight from Excel or Google Sheets. Don’t have data handy? Click “Load sample data” to see an example first.
- Click “Generate Box Plot.” The chart renders instantly, together with the five-number summary, the interquartile range (IQR), and any outliers found by the 1.5 × IQR rule.
- Customize the chart. Switch between vertical and horizontal orientation, and add a chart title and axis labels so the plot is ready for your homework, report, or slide deck.
- Download your plot. Click “Download PNG” to save a high-resolution image you can paste into any document.
How to Read a Box Plot
Every part of a box plot answers a specific question about your data:
- The line inside the box is the median — the middle value of the dataset. Half of your numbers are above it, half are below it.
- The box itself runs from Q1 (the 25th percentile) to Q3 (the 75th percentile). Its length is the interquartile range, or IQR, which measures how spread out the middle half of your data is. A short box means your values are tightly clustered; a long box means they vary a lot.
- The whiskers extend from each side of the box to the smallest and largest values that still fall within 1.5 × IQR of the box edge.
- Points beyond the whiskers are outliers — values so far from the rest that they deserve a second look. They might be data-entry errors, or the most interesting observations in your dataset.
- Skewness shows up as asymmetry. If the right whisker is much longer than the left one, your data is right-skewed (a few large values pull the distribution out). If the median line sits near the bottom of the box, the middle 50% is packed toward the lower end.
To compare two or more groups, draw their box plots side by side on the same scale: differences in medians, box lengths, and whisker ranges become obvious immediately — which is exactly what box plots were invented for.
Frequently Asked Questions
How do you make a box and whisker plot?
By hand, you follow five steps: (1) order your data from smallest to largest; (2) find the median, which splits the data in half; (3) find Q1, the median of the lower half, and Q3, the median of the upper half; (4) draw a box from Q1 to Q3 with a line at the median; (5) extend whiskers to the smallest and largest values within 1.5 × IQR of the box, and mark anything further out as an outlier. Or skip all five steps: paste your numbers into the box and whisker plot maker above and the chart is drawn for you.
What are the 5 numbers in a box and whisker plot?
The five-number summary consists of the minimum, the first quartile (Q1), the median (Q2), the third quartile (Q3), and the maximum. Q1 is the 25th percentile — a quarter of the data falls below it — and Q3 is the 75th percentile. Together these five values describe the center, spread, and range of any dataset, which is why they form the basis of every box plot.
How do you find outliers in a box and whisker plot?
The standard method is the 1.5 × IQR rule. First calculate the interquartile range: IQR = Q3 − Q1. Then set two fences: a lower fence at Q1 − 1.5 × IQR and an upper fence at Q3 + 1.5 × IQR. Any value below the lower fence or above the upper fence is an outlier, drawn as an individual point beyond the whiskers. This box plot maker applies the rule automatically and lists every outlier it finds under the chart.
Can you make a box and whisker plot in Excel?
Yes. In Excel 2016 and later, select your data, go to Insert → Insert Statistic Chart → Box and Whisker. It works, but the customization options are limited — changing whisker definitions, styling outliers, or labeling quartiles is awkward. A faster workflow: generate the chart with this free online tool, download the PNG, and drop it straight into your spreadsheet or report.
Why are my quartiles slightly different from Excel’s?
There are several accepted methods for calculating quartiles, and they can give slightly different Q1 and Q3 values for small datasets. This tool uses the median-of-halves method taught in most textbooks: Q1 is the median of the lower half of the data and Q3 is the median of the upper half. Excel uses a different percentile interpolation (its QUARTILE.INC function), which is why the numbers can differ by a small amount. Both are correct — they just follow different conventions.
Privacy
This box plot generator runs entirely in your browser. The numbers you enter are processed locally by JavaScript and never uploaded to a server, stored, or shared with any third party. You can use it offline once the page has loaded.