The **interquartile** **range**, often denoted IQR, is a way to measure the spread of the middle 50% of a dataset. It is calculated as the difference between the first quartile (Q1) and the third quartile (Q3) of a dataset.

Note that *quartiles* are simply values that split up a dataset into four equal parts.

The IQR is often used to measure the spread of values in a dataset because it’s known to be resistant to outliers. Since it only tells us the spread of the middle 50% of the dataset, it isn’t affect by unusually small or unusually large outliers.

This makes it a preferable way to measure dispersion compared to a metric like the range, which simply tells us the difference between the largest and the smallest values in a dataset.

This tutorial explains how to calculate the IQR for a given dataset in Google Sheets.

**Example: How to Calculate IQR in Google Sheets**

Use the following steps to calculate the interquartile range (IQR) of a dataset in Google Sheets.

**Step 1: Enter the data.**

First, enter all of the values of a dataset into one column:

**Step 2: Calculate the first and third quartiles.**

Next, we’ll use the **QUARTILE() **function to calculate the first (Q1) and third (Q3) quartiles of the dataset.

Note that this function uses the following syntax:

**QUARTILE(data, quartile_number)**

where:

**data:**An array of data values**quartile_number:**The quartile to calculate

The following image shows the formulas to use to calculate Q1 and Q3 for this dataset:

**Step 3: Calculate the IQR.**

Lastly, we can subtract the first quartile (Q1) from the third quartile (Q3) to obtain the interquartile range:

The interquartile range turns out to be **16**. This tells us the spread of the middle 50% of values in our dataset.

**Additional Resources**

How to Calculate the Interquartile Range (IQR) in Excel

How to Calculate Standard Deviation in Google Sheets

How to Calculate a Five Number Summary in Google Sheets

How to Make a Box Plot in Google Sheets