How to Change Mark Type in Tableau

Changing the “Mark Type” in Tableau is at the heart of turning a table of raw data into an insightful visualization. It’s what transforms your numbers into bars, lines, circles, and shapes that tell a story. This guide will walk you through what Marks are, where to find them, and how to change them to build the charts you need.

What Are 'Marks' in Tableau, Anyway?

In the simplest terms, a Mark is the visual representation of your data in a Tableau worksheet. It's the building block of your chart. When you're looking at a visualization, every bar, every circle, and every line segment you see is a "Mark."

Think of it like this:

• In a bar chart, each individual bar is a mark.
• In a line chart, each point along the line is a mark (and the line connects them).
• In a scatter plot, each dot is a mark.
• In a text table, each number displayed in a cell is a mark.

The Marks card in Tableau is your command center for controlling what these building blocks look like and how they behave. You use it to decide if your data should be shown as a bar or a line, and you also use it to control properties like color, size, text labels, and more. Understanding this one card is crucial for mastering Tableau.

Finding and Using the Marks Card

Before you can change the Mark Type, you first need to locate the Marks card. It’s always in the same place on your Tableau worksheet view.

Look to the left of your main visualization canvas. Below the "Pages" and "Filters" shelves, you'll see a box labeled Marks. This card is central to everything you'll do visually in the sheet.

Inside the Marks card, you’ll see several key properties, but the most important one for our purpose is the dropdown menu at the top. By default, it’s set to Automatic. This means Tableau will try to guess the best visualization based on the data fields (pills) you’ve placed on your Columns and Rows shelves.

The dropdown menu contains all the different Mark types available:

• Automatic: Tableau's best guess.
• Bar: For creating bar charts.
• Line: For creating line charts, ideal for time-series data.
• Area: Similar to a line chart but fills the area below the line.
• Square, Circle, Shape: Used for scatter plots or symbol maps.
• Text: For creating text tables or crosstabs.
• Map: Used when you plot geographic data.
• Pie: For creating pie charts (use with caution!).
• Gantt Bar: For creating Gantt charts to show duration.
• Polygon: For custom-shaped maps or diagrams.

Step-by-Step Guide to Changing Your Mark Type

The best way to learn is by doing. Let's walk through a few common examples of how you'd change the mark type to create different charts using the Sample - Superstore data in Tableau.

Example 1: Turning a Text Table into a Bar Chart

Generating a simple table is often the first thing new users do. Let's start there and convert it into a much more effective bar chart.

1. Drag the Category dimension to the Rows shelf.
2. Drag the Sales measure to the Text property on the Marks card.

You now have a simple text table showing the total sales for each product category.

This is okay, but a bar chart would make comparing the categories much easier. Here's how to change it:

1. Navigate to the Marks card. You'll see the dropdown is likely set to 'Automatic' and shows a 'T' icon, indicating it's a Text mark type.
2. Click the dropdown menu.
3. Select Bar from the list.

Instantly, your text table disappears, and you'll see vertical lines where the text used to be. The view might look odd because we haven't told Tableau how long to make the bars. The final step is to put the Sales measure on the Columns shelf.

1. Click and drag the SUM(Sales) pill from the Text property on the Marks Card up to the Columns shelf.

And just like that, you have a perfectly formatted horizontal bar chart. You successfully changed the Mark Type from Text to Bar to turn raw numbers into a clear, comparative visualization.

Example 2: Creating a Line Chart to Show a Trend

Line charts are the best choice for showing how a value changes over time. Let's see how sales have trended over time.

1. Drag the Order Date dimension to the Columns shelf. Tableau will probably default to YEAR(Order Date). Right-click on this pill, go down to the second group of date values, and select Month (the continuous one with a green calendar icon).
2. Drag the Sales measure to the Rows shelf.

Because you're using a continuous date on Columns and a measure on Rows, Tableau's 'Automatic' setting is smart enough to generate a line chart for you. But to be sure, you can always go to the Marks card dropdown and manually confirm that Line is selected. You've officially created a view where the fundamental Mark is a Line, connecting points for each month.

Example 3: Building a Scatter Plot to See Relationships

A scatter plot helps you identify relationships between two different measures. For example, is there a connection between a product's sales and its profit?

1. Drag the Sales measure to the Columns shelf.
2. Drag the Profit measure to the Rows shelf.

Right now, your chart will show just one mark. That's because Tableau has aggregated all sales and all profits into a single point. To make this a useful scatter plot, we need to tell Tableau what level of detail to create the marks at.

1. Find a dimension like Product Name in your data pane.
2. Drag Product Name and drop it onto the Detail property on the Marks card.

Now, Tableau will create a mark for every single product, plotting each one based on its total sales and total profit. Notice that the Mark Type is likely 'Automatic' (as a Circle or Square). You can click the dropdown and choose Circle to make it look like a classic scatter plot.

Tips for Choosing the Right Mark Type

Knowing how to change the mark type is half the battle, knowing which one to use is the other half. Here's a quick cheat sheet:

• Bar Chart: Use when you want to compare numerical values across different categories. Example: Sales by City.
• Line Chart: Use to track a value's performance over a continuous period. Example: Website sessions per day over the last month.
• Area Chart: Use like a line chart, but to emphasize the magnitude of change or the total volume over time. Example: Total number of tickets closed by a support team each week.
• Scatter Plot (Circle/Square): Use to show the correlation between two different numerical measures. Example: Marketing Spend vs. Customer Acquisition Cost for different campaigns.
• Text Table: Use only when you need to see precise figures and the ability to compare them visually is less important. Example: A detailed financial statement.
• Map: Use when you have geographical data (Country, State, City, Zip Code). Example: Profit by State.

Advanced Technique: Combining Two Mark Types

One of the most powerful features in Tableau is the ability to use two different mark types in the same visualization using a dual-axis chart. This is great for comparing two measures that have very different scales. Let’s create a chart showing monthly sales (as bars) and the profit ratio (as a line) on the same view.

1. First, set up a bar chart showing Sales by Month. Drag Order Date (as continuous month) to Columns and Sales to Rows. Make sure the mark type is set to Bar.
2. Now, drag the Profit Ratio measure from your data pane and place it onto the Rows shelf right next to the SUM(Sales) pill. You’ll now see two separate charts stacked on top of each other.
3. Notice that on the Marks card, you now have layers: one for All, one for SUM(Sales), and one for AGG(Profit Ratio). This lets you control each chart independently. Click on the AGG(Profit Ratio) layer on the Marks card.
4. With this layer active, change its Mark Type from Bar to Line. Now you have a bar chart and a line chart. The last step is to combine them.
5. On the Rows shelf, right-click the AGG(Profit Ratio) pill and select Dual Axis from the menu.

Your charts are now overlaid on top of each other! As a best practice, always right-click the secondary axis (on the right) and select Synchronize Axis if the measures use a similar scale, though in this case (Dollars vs. Percentage) it's better to leave them independent.

This technique opens up a huge new set of visualization possibilities, and it all starts with understanding how to control each layer through the Marks card.

Final Thoughts

Understanding and manipulating the Marks card is the gateway to creative and effective data visualization in Tableau. It’s the control panel that bridges an abstract grid of numbers to a compelling story you can share with your team. By changing the Mark Type, you're not just clicking a button, you're choosing the best possible language to communicate your data's insights.

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