# InterQuartile Range (IQR) Calculator

Free InterQuartile range (IQR) calculator to find the Inter-quartile range, first quartile, third quartile and median from the set of observed numerical data. IQR measures the difference between 3rd and 1st quartile.

## InterQuartile Range Calculation

Free InterQuartile range (IQR) calculator to find the Inter-quartile range, first quartile, third quartile and median from the set of observed numerical data. IQR measures the difference between 3rd and 1st quartile.

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Use our IQR calculator to find the interquartile range from the set of numerical values. In statistical dispersion, Interquartile range (IQR) is the measurement of difference between the third and the first quartiles. Mathematically, it is obtained when the 1st quartile is subtracted from the 3rd quartile. IQR is otherwise called as midspread or middle fifty. It is expressed as IQR = Q^{3} - Q^{1}. The IQR can be clearly plotted in box plot on the data. Find IQR using interquartile range calculator which is the most important basic robust measure of scale and variability on the basis of division of data set in the quartiles. Use this online interquartile range (IQR) calculator to find the values of first quartile, third quartile, median and inter quartile range.

#### Formula:

InterQuartile Range (IQR) = Third Quartile - First Quartile.

#### Example

Let us consider the following numbers: 1, 4, 5, 6, 6, 7, 11, 12, 15, 17

**Step 1:**

Q1 is the middle value in the first half of the data set i.e 5

**Step 2:**

Q3 is the middle value in the second half of the data set i.e 12

**Step 3:**

Sum of all the numbers divided by total number of values

Median = 1 + 4 + 5 + 6 + 6 + 7 + 11 + 12 + 15 + 17 / 10

= 6.5

**Step 4:**

The interquartile range is Q3 minus Q1, so IQR = 12 - 5= 7