# How to Calculate the Interquartile Range in Excel?

In statistics, the **five-number summary** is mostly used as it gives a rough idea about the dataset. It is basically a summary of the dataset describing some key features in statistics. The five key features are :

**Minimum value:**It is the minimum value in the data set.**First Quartile, Q1**: It is also known as the lower quartile where 25% of the scores fall below it.**Median (middle value) or second quartile**: It is basically the mid-value in the dataset.**Third Quartile, Q3**: It is also known as the Upper quartile in which 25% of the data is above it and the rest 75% falls below it.**Maximum value**: It is the maximum value in the dataset.

Using two quartiles of the five-number summary we can easily calculate the **IQR** abbreviated as** Interquartile Range**.

In this article, we are going to see how to calculate the Interquartile range in Excel using a sample dataset as an example.

## Interquartile Range

In terms of Mathematics, it is basically defined as the **difference** between the **third quartile (75th percentile) and the first quartile (25th percentile)**.

Q3-Q1

IQR denotes the middle 50% hence also known as **midspread **or **H-spread** in statistics. It can be easily observed using a **box plot**.

The vertical lines of the rectangular box plot denote the Interquartile range which lies between Quartile 1 and Quartile 3.

**Example:** Consider the dataset consisting of the BMI of ten students in a class.

Now, in order to calculate the IQR we need to first calculate the two quartile values **Q1 and Q3**. The function used is :

QUARTILE(Array,quart) // Used in Excel 2007 version and lower or QUARTILE.INC(Array,quart) // Used in latest version of Excel Array : Cell range quart : The five quart values from 0 to 4 0- Minimum value 1- First Quartile (25 percent) 2- Median Value (50 percentile) 3- Third Quartile (75 percentile) 4- Maximum value

### Calculation

Follow the below steps to calculate the same:

**Step 1:** Insert the dataset.

**Step 2:** Select any cell where you want to write the formula to calculate the values of Q1, Q3, and IQR.

**Step 3: **First find the values of Q1 and Q3 using the quart values as 1 and 3 respectively.

The dataset is stored in **column “A” **of the worksheet and the observations are stored from cell **A2 to A11**.

So the array will start from A2 and end at A11.

You can also find the remaining three parameters of a five-number summary using the same formula just by changing the quart value. But to find the IQR, we only need the values of **Q1 and Q3**.

The value of Q3 is stored in cell D4 and that of Q1 in cell D3. The formula will be :

=Cell_no_Q3-Cell_no_Q1

The **Interquartile range** for the above dataset turns out to be **6.5**.

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