Box Plot Maker — Interquartile Range (IQR) & Whisker Distribution Graph
A box-and-whisker plot summarizes a probability distribution via its quartiles—drawing a central box from $Q_1$ (25th percentile) to $Q_3$ (75th percentile) bisected by the Median ($Q_2$), with whiskers extending across the spread ($IQR = Q_3 - Q_1$).
Tip: Paste Excel or Google Sheets rows (Ctrl+V / ⌘V) directly into any cell.
| # | Label | ||||
|---|---|---|---|---|---|
| 1 | |||||
| 2 | |||||
| 3 | |||||
| 4 | |||||
| 5 | |||||
| 6 |
Interquartile Range: IQR = Q3 - Q1. Whisker span: Lower = max(0, Q1 - 0.85 * IQR), Upper = Q3 + 0.85 * IQR. Quartile skew coefficient: ((Q3 - Q2) - (Q2 - Q1)) / IQR.
Chart Design & Use-Case Tips
- 01Interquartile Range: IQR = Q3 - Q1. Whisker span: Lower = max(0, Q1 - 0.85 * IQR), Upper = Q3 + 0.85 * IQR. Quartile skew coefficient: ((Q3 - Q2) - (Q2 - Q1)) / IQR.
- 02Enter the Median (Q2) in the first column, the 25th Percentile (Q1) in the second column, and the 75th Percentile (Q3) in the third column.
- 03A taller box indicates wider interquartile dispersion (higher variance), while an off-center median line inside the box reveals skewness.
- 04Compare whether the boxes of two groups overlap to gauge statistical separation at a glance.
Frequently Asked Questions
How are the three columns in the table mapped to the Box Plot?+
Column 1 (Series A) sets the Median (Q2, 50th percentile), Column 2 (Series B) sets the lower box edge (Q1, 25th percentile), and Column 3 (Series C) sets the upper box edge (Q3, 75th percentile).
Why use a box plot instead of a bar chart of averages?+
A bar chart of means hides spread, skewness, and outliers. A box plot reveals the middle 50% of data (IQR), median robustness, and distributional symmetry across multiple groups.
What if Q1 and Q3 are accidentally entered in reverse order?+
The engine automatically sorts the quartile bounds so the box always spans from min(Q1, Q3) to max(Q1, Q3) without rendering errors.