Calculate q1.
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Interquartile Range (IQR) Calculator
Quick answer
If values are 12, 15, 15, 18, 22, 27, 31, the interquartile range is 9.5.
Interquartile range: IQR = Q3 − Q1.
Enter your values
- 12
- 15
- 15
- 18
- 22
- 27
- 31
7 values
Interquartile Range
9.5
The spread of the middle 50% of the data, from the first quartile to the third — less affected by extreme outliers than the full range.
You enter Values 12, 15, 15, 18, 22, 27 … (7 values). You get Interquartile Range 9.5.
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About the Interquartile Range (IQR) Calculator
The interquartile range (IQR) is the distance between the first and third quartiles, so it describes the spread of the middle half of your data. Because it ignores the extremes, it is a steadier measure of spread than the range.
For 12, 15, 15, 18, 22, 27 and 31, Q1 is 15, Q3 is 24.5 and the IQR is 9.5.
Interquartile range
IQR = Q3 − Q1
Things to keep in mind
- Outliers are often defined as values below Q1 − 1.5 × IQR or above Q3 + 1.5 × IQR.
- A small IQR means the middle values are tightly grouped.
- Different quartile methods can change the IQR slightly.
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A quick guide to Interquartile Range
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How to Use the Interquartile Range Calculator
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What is Interquartile Range?
This statistics & probability tool works out your interquartile range instantly, so you don't have to do the math by hand.
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What Affects Your Interquartile Range
Your interquartile range depends on the values below.
Values
Changing your values changes your interquartile range.
Example Result
Here's what you can expect from an interquartile range calculation:
- Interquartile Range
- 9.5
Frequently Asked Questions
- How to calculate interquartile range?
- Fill in values in the Interquartile Range (IQR) Calculator above and your interquartile range is calculated instantly. Change any value to see how the result responds.
- What does an example interquartile range calculation look like?
- If values are 12, 15, 15, 18, 22, 27, 31, the interquartile range is 9.5.
- Is this calculator free to use?
- Yes — every calculator on this site is completely free, with no sign-up or account required.
- How accurate is this calculator?
- It uses the standard formula and calculates on our server for every request, so results are precise for the values you enter.
- Is my data saved anywhere?
- No. Nothing you enter is stored or sent anywhere unless you choose to share a link with your values included.
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