IQR Calculator
Calculate the interquartile range (Q3 − Q1) as a robust measure of spread.
About IQR Calculator
The interquartile range (IQR) is Q3 minus Q1. It measures the spread of the middle 50% of data and is resistant to outliers, unlike the full range.
Formula
IQR = Q3 − Q1
- Q1
- First quartile
- Q3
- Third quartile
Worked example
With the default values below, IQR Calculator returns IQR of 6.0000. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Data (comma separated)
- 2, 4, 6, 8, 10, 12, 14
Results
- IQR
- 6.0000
- Q1
- 5.0000
- Q3
- 11.0000
Step by step
- 1Values used
- 2Formula applied
- 3IQR= 6.0000
- 4Q1= 5.0000
- 5Q3= 11.0000
Assumptions and limits
- The result is derived only from the single input listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why is IQR preferred over range?
IQR ignores the extreme values and only measures the spread of the middle half of the data, making it robust against outliers.
How is IQR used to detect outliers?
Values below Q1 − 1.5×IQR or above Q3 + 1.5×IQR are flagged as outliers using Tukey's fence method.