How to Create Age Groups in Tableau

Analyzing customer data by age is essential, but a list of individual ages from 18 to 80 isn't very useful on its own. To uncover real insights, you need to cluster those ages into logical groups like "18-24" or "45-54." This article will show you three different ways to create custom age groups directly within Tableau, so you can transform raw numbers into a clear demographic story.

Why Group Ages in Tableau?

Working with individual ages can make your charts crowded and difficult to read. Imagine a bar chart with 50 different bars, one for each age. It’s nearly impossible to spot trends or make comparisons. By grouping ages, you can:

• Simplify Visualizations: Instead of dozens of data points, you get a handful of easy-to-understand categories, making your charts cleaner and more impactful.
• Identify Key Demographics: You can quickly see which age brackets are your most engaged customers, highest spenders, or most frequent website visitors.
• Compare Generational Trends: Grouping ages allows you to compare behaviors between generations like Millennials, Gen X, and Baby Boomers, which is incredibly valuable for marketing and product development.

Essentially, grouping turns a noisy dataset into a strategic asset. Now, let's get into how to do it.

Step 1: Make Sure You Have an Age Field

Before you can create age groups, you need a field in your dataset that contains each person's age. If you already have a field named "Age" with numeric values, you're all set. But often, datasets contain a "Birth Date" instead.

If that's your starting point, you first need to create a calculated field to determine the current age of each person. It’s a simple calculation that subtracts the birth year from the current year.

Here’s how to do it:

1. In Tableau, go to the top menu and select Analysis > Create Calculated Field...
2. Name your new field something clear, like "Calculated Age."
3. In the formula box, enter the following code:

DATEDIFF('year', [Birth Date], TODAY())

Let's quickly break this down:

• DATEDIFF(): This is Tableau's function for calculating the difference between two dates.
• 'year': This tells the function you want the result in years.
• [Birth Date]: This is the name of your field that contains the birth dates. Make sure it matches your field name exactly.
• TODAY(): This function returns the current date.

Click "OK," and you'll see your new "Calculated Age" field appear in the Data pane. Now you're ready to create your groups.

Method 1: Creating Groups with Bins (The Quickest Method)

The fastest way to group a numeric field like age is by using Tableau’s "Bins" feature. Bins automatically chop up a continuous measure into equal-sized chunks or groups. This is perfect for quick, exploratory analysis when you don't need highly customized ranges.

How to Create Age Bins

1. In the Data pane on the left, find your "Age" field (or the "Calculated Age" field you just created).
2. Right-click on the field and select Create > Bins...
3. A "Create Bins" dialog box will pop up. Here, you’ll set the Size of bins. This number determines the size of each age group.

• For example, if you enter 10, Tableau will create groups of 0-9, 10-19, 20-29, and so on.
• If you enter 5, it will create groups of 0-4, 5-9, 10-14, etc.

1. Click "OK."

Tableau will automatically create a new dimension in your Data pane called "Age (bin)." You can now drag this field onto your Rows or Columns shelf to see your data aggregated by these new age groups. Voila! You have an instant histogram.

Pros and Cons of Using Bins

• Pros: It’s incredibly fast and requires zero formula writing. This is the go-to method for a first pass at your data.
• Cons: The biggest limitation is a lack of flexibility. All bins must be the exact same size. You can't create custom, business-centric groups like "18-24," "25-39," and "40-65." Your first bin also starts at zero, which may not be relevant for your analysis.

Method 2: Using a Calculated Field (The Most Flexible Method)

When you need full control over your age groups - with custom ranges of varying sizes - calculated fields are the way to go. This method involves writing a simple IF/THEN statement to assign each age to a specific group you define. It may sound technical, but it’s straightforward once you see the logic.

How to Create Age Groups with a Formula

1. Go to Analysis > Create Calculated Field... from the top menu.
2. Name your field something descriptive, like "Age Group."
3. In the formula editor, you'll write an IF...ELSEIF...END statement. Here’s a common template you can adapt:

IF [Age] >= 18 AND [Age] <= 24 THEN "18-24"
ELSEIF [Age] >= 25 AND [Age] <= 34 THEN "25-34"
ELSEIF [Age] >= 35 AND [Age] <= 49 THEN "35-49"
ELSEIF [Age] >= 50 AND [Age] <= 64 THEN "50-64"
ELSE "65+"
END

Breaking Down the Formula:

• IF [Age] >= 18 AND [Age] <= 24: Tableau checks if the value in the "Age" field is between 18 and 24 (inclusive).
• THEN "18-24": If the condition is true, it assigns that record the text label "18-24."
• ELSEIF...: If the first condition isn't met, Tableau evaluates the next condition, and so on.
• ELSE "65+": The final ELSE is a catch-all. Any age not fitting the previous categories (like 65 or older) will be labeled "65+."
• END: This signals the end of the calculation.

Once you click "OK," your new "Age Group" dimension will appear in the Data pane. You can now use this field in any of your visualizations just like any other dimension.

Pros and Cons of Using Calculated Fields

• Pros: This method gives you complete control. You can create precisely the groups your analysis requires, with meaningful labels and unequal interval sizes. It's the most robust and scalable approach.
• Cons: It requires writing a formula, which can feel intimidating for beginners. However, once you have the template, you can easily copy, paste, and adjust it for any grouping task.

Method 3: Creating a Group Manually (For Ad-Hoc Analysis)

Tableau also allows you to manually group dimension members directly from a visualization. This method is highly visual and intuitive, making it a good choice for smaller datasets or for making quick, on-the-fly groupings to explore a theory.

How to Manually Group Ages

1. Start by creating a visualization that shows all the individual ages. A vertical bar chart is perfect for this. Drag "Age" to Columns and the count of your records (e.g., "Number of Records" or COUNT([Customer ID])) to Rows.
2. Now, select the members you want to group together. Hold down the Ctrl key (or Command on a Mac) and click on the bars or axis labels for the ages you want in your first group (e.g., click 18, 19, 20, 21, 22, 23, and 24).
3. With the ages selected, hover over one of them until the pop-up tooltip appears, then click the paperclip icon, which represents the "Group" command.
4. Tableau will immediately lump those selected ages into a single group and create a new field in your Data pane called "Age (group)."
5. You can now rename your groups. Right-click on a new group label in your visualization (it will have a default name like "18, 19, 20,...") and select Edit Alias. Change it to something clean, like "18-24." Repeat this for all your groups.

Pros and Cons of Manual Grouping

• Pros: It’s very interactive and doesn't require any code. It's great for quick, exploratory data segmentation.
• Cons: This method is not dynamic. If your underlying data is refreshed and new ages appear, they won't automatically be included in your groups. It’s also tedious for grouping a wide range of values and is better suited for categorical data than for continuous numbers like age.

Visualizing and Sorting Your New Age Groups

Once you've created your "Age Group" dimension, the final step is to use it. A simple bar chart is often the most effective way to compare a measure across age groups.

One common hiccup you might encounter is sorting. When you create groups using a calculated field, the result is a string (text). Tableau will, by default, sort text alphabetically. This can mess up your chart's logic, leading to an order like: "18-24", "25-34", "50-64", "35-49."

To fix this, you can manually reorder the groups. Simply click and drag the "Age Group" pills on the Columns or Rows shelf into the correct chronological order.

Final Thoughts

Grouping data is a fundamental skill in data analysis, and Tableau provides multiple ways to accomplish it. For quick exploration of evenly-sized clusters, bins are your best friend. For robust, repeatable, and fully customized analysis that aligns with business logic, the calculated field method is the clear winner.

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