# Interquartile Range

*Math & Statistics — Finicade finance glossary*

The interquartile range is the distance between the 25th and 75th percentiles — the width of the middle half of the data. It's a measure of spread that ignores the tails entirely, making it robust where standard deviation is not. The common outlier rule of thumb, flagging anything beyond 1.5 IQRs from a quartile, is what draws the whiskers on a box plot.

**Formula:** `IQR = 75th percentile − 25th percentile`

**Also known as:** IQR, quartiles, box plot

**Related terms:** [Percentile](https://finicade.com/glossary/percentile), [Standard Deviation](https://finicade.com/glossary/standard-deviation), [Outlier](https://finicade.com/glossary/outlier), [Mean, Median and Mode](https://finicade.com/glossary/mean-median-mode), [Volatility](https://finicade.com/glossary/volatility)

**Taught in:** Stat Dojo — Boxplots, Quartiles & Outliers

Source: https://finicade.com/glossary/interquartile-range