How to Find Quartiles in Excel: A Step-by-Step Guide for Beginners

Figuring out quartiles in Excel can seem confusing at first but it’s actually pretty straightforward once you know the different methods. As a beginner Excel user myself I was intimidated by the fancy statistical terms like “quartiles” and “percentiles”. But I’ve learned that finding quartiles in Excel only requires a simple built-in function.

In this comprehensive guide, I’ll walk through the step-by-step process to calculate quartiles in Excel using examples and visuals. You’ll learn the difference between quartiles and percentiles, how to use the QUARTILE.INC and QUARTILE.EXC functions and some real-world examples of quartiles in Excel. Let’s get started!

What are Quartiles?

Before diving into the how-to, it helps to understand what quartiles are in the first place.

Quartiles are a type of percentile that specifically divide data into four equal groups. The four quartile groups are:

• First quartile (Q1) – lowest 25% of data
• Second quartile (Q2) – middle 50% of data
• Third quartile (Q3) – highest 25% of data
• Fourth quartile (Q4) – the maximum value

Basically, quartiles split data into fourths. The second quartile equals the median, which most of us learned back in elementary school math class.

Quartiles are useful for analyzing trends and distributions in large data sets. Some examples of using quartiles include:

• Scoring tests – teachers can assign grades based on quartiles
• Marketing research – companies may analyze customer spending by quartile
• Sales data – sales reps can compare their performance by quartile

Now that we’ve got the basics down, let’s see how to actually calculate quartiles in Excel.

Using the QUARTILE.INC Function

Excel has a built-in QUARTILE function to calculate quartiles for us. There are two versions:

• QUARTILE.INC – Includes the minimum and maximum values
• QUARTILE.EXC – Excludes the minimum and maximum values

For this example, we’ll use QUARTILE.INC. Here are the step-by-step instructions:

1. Organize your data set in one column in Excel. For this example, our data is in cells A2 through A20.

2. Click any blank cell where you want to display the quartile result. I’ll put mine in C2.

3. Type the formula =QUARTILE.INC(. Don’t hit Enter yet!

4. Highlight the data range for the quartile calculation. In our case, it’s A2:A20.

5. The formula will auto-populate with the range like this: =QUARTILE.INC(A2:A20)

6. Next, add a comma after the data range followed by the quartile number you want:

   • First quartile: =QUARTILE.INC(A2:A20,1)
   • Second quartile: =QUARTILE.INC(A2:A20,2)
   • Third quartile: =QUARTILE.INC(A2:A20,3)
   • Fourth quartile: =QUARTILE.INC(A2:A20,4)

7. Hit Enter and the first quartile result will be calculated!

That’s it! To find other quartiles, just change the number after the comma in the formula.

Here’s a visual step-by-step guide to using QUARTILE.INC in Excel:

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Now let’s try a real example with number values and see how the quartiles actually divide up the data set.

Real Example with the QUARTILE.INC Function

Let’s say we have a data set of exam scores for 20 students:

<insert image 2>

We want to calculate the quartiles to see how the exam scores were distributed.

Following the same steps as above, we get:

• First quartile (Q1) = =QUARTILE.INC(A2:A21,1) = 71
• Second quartile (Q2) = =QUARTILE.INC(A2:A21,2) = 83
• Third quartile (Q3) = =QUARTILE.INC(A2:A21,3) = 92

This divides the scores into fourths:

• 0 to 71 = lowest 25%
• 71 to 83 = second lowest 25%
• 83 to 92 = second highest 25%
• 92 to 100 = highest 25%

The instructor can now quickly see how students performed on the exam and assign letter grades based on the quartiles.

Using the QUARTILE.EXC Function

The QUARTILE.EXC function works exactly the same as QUARTILE.INC, with one key difference:

QUARTILE.EXC excludes the minimum and maximum values when calculating the quartiles.

Let’s revisit our exam score example from above, but this time use QUARTILE.EXC:

<insert image 3>

The quartiles are slightly different with the exclusive method:

• First quartile (Q1) = =QUARTILE.EXC(A2:A21,1) = 73
• Second quartile (Q2) = =QUARTILE.EXC(A2:A21,2) = 83
• Third quartile (Q3) = =QUARTILE.EXC(A2:A21,3) = 91

Notice the first and third quartiles changed compared to QUARTILE.INC, because the min and max values are excluded.

Use QUARTILE.EXC when you don’t want the outliers to skew the quartile calculations.

Quartiles vs. Percentiles

New Excel users often confuse quartiles and percentiles. What’s the difference?

While quartiles split data into fourths, percentiles split data into hundredths. Common percentiles include:

• 25th percentile = first quartile
• 50th percentile = second quartile (median)
• 75th percentile = third quartile

So quartiles are a special type of percentile, where you specifically look at 25%, 50%, and 75% of the data set.

Excel has specific functions for percentiles too, like PERCENTILE.INC and PERCENTILE.EXC. Just remember – percentiles are more granular at the hundredth percentile level.

Best Practices When Finding Quartiles

Here are a few tips to keep in mind when using quartiles in Excel:

• Double check your data is sorted from smallest to largest. This ensures an accurate quartile calculation.

• Use QUARTILE.INC when you want to include all data values, including outliers.

• Use QUARTILE.EXC to exclude outliers or very high/low values in your data set.

• Format the quartile cells to display with zero decimal places. Quartiles should be whole numbers.

• Add labels like “Q1” and “Third Quartile” so it’s clear what the values represent.

Common Uses for Quartiles

While this guide focused on the formulas for finding quartiles, let’s briefly look at some real-world examples where you’d actually use quartile analysis:

Scoring Tests

Teachers often grade on a curve based on quartiles. The lowest quartile of scores may get an F, the middle two quartiles a C and B, and the top quartile an A.

Sales Performance

Sales managers can divide reps into quartiles based on total sales numbers. The top quartile gets praise and bonuses, while the bottom quartile may need additional coaching.

Marketing Research

Market researchers group survey responses into quartiles. For example with income data – the first quartile is low income, middle quartiles are middle income, and fourth quartile is high income.

There are many more applications for quartiles across business, statistics, sports analytics, and more. But this gives a taste of how they can be used to group and compare data sets.

Limitations of Quartiles

While useful in many cases, quartiles do have some limitations to be aware of:

• Sample size matters – quartiles are less meaningful with very small data sets
• Can oversimplify data – you lose granularity by grouping into just four buckets
• Sensitive to outliers – extremely high or low values can skew quartile bounds

If you encounter any of these issues, it may be better to use more robust statistical methods. But for simple segmentation and comparison, quartiles provide a snapshot view into your data distribution.

Next Steps and Resources

That concludes my beginner’s guide to calculating quartiles in Excel! Here are some next steps:

• Practice calculating quartiles with sample data sets
• Try using quartiles to analyze real data relevant to your work
• Read Microsoft’s official docs on the [QUARTILE function](https://support.microsoft.com/en-us/office/quartile-function-93cf8f62