Box Plot Calculator
Generate complete box plot data for visualization and analysis.
Box Plot Components
Left Whisker: Extends from Q1 to minimum (or 1.5×IQR bound)
Box: Spans Q1 to Q3, represents middle 50% of data
Median Line: Divides box at 50th percentile
Right Whisker: Extends from Q3 to maximum (or 1.5×IQR bound)
Box Plot Interpretation Guide
| Feature | What It Means | Example |
|---|---|---|
| Centered median | Symmetric distribution | Roughly normal data |
| Median off-center | Skewed distribution | Income data (right-skewed) |
| Narrow box | Clustered data | Small IQR |
| Separate points | Outliers beyond whiskers | Beyond 1.5×IQR |
Frequently Asked Questions
What is a box plot?
Visual summary of data distribution using five number summary. Box shows middle 50%, line shows median, whiskers show extremes. Clearly reveals shape and outliers.
What do the five parts of a box plot represent?
Left whisker = minimum, left box edge = Q1, middle line = median, right box edge = Q3, right whisker = maximum. Together show complete distribution.
What does the box represent?
Box spans Q1 to Q3, containing middle 50% of data. Box height/width shows IQR. Narrow box = clustered. Wide box = spread out.
What do the whiskers represent?
Lines extending from box to min/max values (or to 1.5×IQR boundary). Show range of normal data. Points beyond = potential outliers.
What is the line inside the box?
Median (Q2), the 50th percentile. Divides box into two parts. Position within box shows if median is centered or skewed toward Q1/Q3.
How do I interpret a skewed box plot?
Median line off-center = skewed data. Line closer to Q1 = right-skewed. Line closer to Q3 = left-skewed. Skewness indicates data shape asymmetry.
What are outliers in a box plot?
Points plotted separately beyond whiskers. Usually beyond Q1 - 1.5×IQR or Q3 + 1.5×IQR. Shown as dots or asterisks.
Can two datasets be compared with box plots?
Yes. Side-by-side box plots show medians, spreads, symmetry visually. Easy to compare distributions at a glance.
What information does a box plot hide?
Actual data points, distribution shape within quartiles, sample size. Box plot shows summary, not granularity.
When should I use a box plot?
Comparing groups, checking for symmetry, identifying outliers, summarizing large datasets. Excellent for exploratory data analysis.
How is a box plot different from a histogram?
Box plot: summary visualization, shows five numbers. Histogram: shows frequency distribution across bins. Complementary tools for different purposes.
What is the advantage of box plots?
Simple visual summary, resistant to outliers, easy to compare multiple datasets, shows both center and spread, identifies unusual values clearly.