Interquartile Range Calculator
IQR, quartiles and outlier fences.
Reviewed by James Whitfield · How we check our maths
Your values
ⓘ Live results
Results
- Interquartile range
- 19.75
- Q1
- 19
- Median (Q2)
- 29
- Q3
- 38.75
- Outlier fences
- -10.625 to 68.375
- Outliers found
- 90
Quick answer
The IQR is Q3 minus Q1, covering the middle 50% of the data and resisting the influence of outliers.
The formula
IQR = Q3 − Q1
Worked example
Worked example
Using the values the calculator loads with.
Inputs
- Data values12, 15, 18, 22, 27, 31, 35, 40, 52, 90
Result
- Interquartile range19.75
- Q119
- Median (Q2)29
- Q338.75
- Outlier fences-10.625 to 68.375
- Outliers found90
How to use the Interquartile Range Calculator
- 1Paste your data separated by commas.
- 2Read the quartiles and IQR.
- 3Check the outlier list against your data.
Frequently asked questions
Why use IQR instead of range?
It ignores extreme values, so it describes typical spread better.
What is the 1.5 rule?
Values beyond 1.5 IQR from the quartiles are conventionally flagged as outliers.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error