Box and Whisker Plot Maker

A box and whisker plot (also called a box plot) is a standardized way of displaying a dataset's distribution based on a five-number summary: minimum, Q1, median, Q3, and maximum. The 'box' spans Q1 to Q3, the line inside the box marks the median, and the 'whiskers' extend to the minimum and maximum (excluding outliers when Tukey's method is applied).

The dataset is first sorted in ascending order. Q2 (median) is the middle value. Q1 is the median of the lower half of the data (below Q2), and Q3 is the median of the upper half (above Q2). If the dataset has an even number of values, the median of each half is the average of the two middle values.

The Interquartile Range (IQR) is Q3 minus Q1. It represents the spread of the middle 50% of your data and is a robust measure of variability that is not affected by extreme values or outliers. A larger IQR indicates more spread in the central data.

Tukey's method defines outliers as any data point that falls below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR. These fences are called the lower and upper fences. Points outside these fences are flagged as outliers and are typically plotted as individual dots beyond the whiskers.

When outliers are shown, the whiskers extend to the actual minimum and maximum values in the dataset. When outliers are excluded (Tukey's method), the lower whisker extends to the smallest value still within the lower fence (Q1 − 1.5×IQR), and the upper whisker extends to the largest value within the upper fence (Q3 + 1.5×IQR).

You need at least 5 numeric data points to generate a meaningful box and whisker plot. With fewer than 5 values, quartile calculations become unreliable. Most statistical analyses work best with 20 or more data points.

This tool currently analyzes one dataset at a time and displays its five-number summary with outlier detection. For side-by-side comparison of multiple datasets, you can run each dataset separately and compare the summary statistics shown in the results table.

Enter numeric values separated by commas, spaces, or new lines — for example: 12, 15, 19, 22, 28. The tool automatically ignores empty cells, text labels, and non-numeric entries, so you can paste directly from a spreadsheet or CSV file.