Statistics
Interquartile Range Calculator
Use the interquartile range calculator to summarize the middle 50% of a data set.
IQR
—
- Q1
- —
- Median
- —
- Q3
- —
Student quick launch
Grade planning, algebra checks, and formulas students reach for most.
Study path
Use this calculator with
Follow these when you want the formula behind the answer, a short lesson, or nearby tools in the same topic.
What the interquartile range calculator solves
Use the interquartile range calculator to summarize the middle 50% of a data set.
Formula
How to use it
- Enter a data list.
- The calculator sorts the values.
- Read quartiles and subtract Q1 from Q3.
How to read the answer
IQR measures spread in the middle half of the data and is less sensitive to outliers than range.
Common mistakes and edge cases
- Quartile methods can vary by class or software.
- Do not confuse IQR with full range.
- Small data sets can have coarse quartile positions.
Worked examples
Even count data
IQR
6.25
With outlier
IQR
3
Frequently asked questions
Why use IQR?+
It focuses on the middle 50% and reduces the effect of extreme values.
Can quartiles differ across tools?+
Yes. This calculator uses linear interpolation quantiles.
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Last updated: May 15, 2026