Charts / Glossary
Quartile
A chart word, with the charts that use it.
Definition
Quartiles are the values that cut sorted data into four equal parts; the box in a box plot. The box spans the middle half, from the first quartile to the third.
Updated Nov 2, 2026
- 01The boxFrom the first to the third quartile: the middle half.
- 02The medianThe second quartile, inside the box.
Where you see it
043 · Box plotDistribution · AI data
Common mistakes
Reading the box as the full range
The box is the middle half. The whiskers and dots show the rest.
Box plots with few values
Quartiles of five values say little. Show the points instead.
Questions
What are Q1, Q2 and Q3?
The values a quarter, half and three quarters of the sorted data sit below.
Why show quartiles instead of the range?
They ignore the extremes, so the typical spread reads clearly.
Related terms
- Median
- Whisker
- Outlier
- Distribution
Every chart word, A to Z.
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