Quartile and IQR Calculator
Calculate Q1, median, Q3, interquartile range and review fences from one browser-local data list.
What would you like to do next?
Summarize the middle half of a numeric data set
Enter a list of numbers to calculate the first quartile, median, third quartile and interquartile range. The page also displays lower and upper fences at one and a half times the IQR. These outputs make it easier to inspect the center and spread of a distribution without uploading a spreadsheet or sharing the source values with a remote service.
Treat outlier fences as review signals
A value beyond an IQR fence is not automatically a mistake and can be an important observation. Investigate collection conditions, units and context before excluding anything. Quartile definitions also vary among tools, so this page states its linear interpolation method. Use the same convention across every comparison and retain a documented rule when the result feeds a report or decision.
Frequently asked questions
How is the IQR calculated?
The calculator subtracts Q1 from Q3 after sorting and interpolating the data.
Do the fences delete outliers?
No. They identify values for review and never change the entered data.
Which quartile convention is used?
Q1, median and Q3 use linear interpolation at indexes based on n minus one.