How to Show Month Over Month Change in Tableau

Calculating month-over-month change is one of the most fundamental tasks in data analysis, allowing you to see the immediate trajectory of your business. In this tutorial, we will walk through exactly how to calculate and visualize month-over-month (MoM) growth in Tableau, starting with a simple, one-click method and moving on to more flexible techniques.

Why Bother Tracking Month-over-Month Change?

Before jumping into the "how," let's quickly touch on the "why." Tracking MoM change helps you move beyond raw numbers to understand momentum. Are your sales numbers just high, or are they growing? Did that new marketing campaign actually move the needle this month?

Monitoring MoM metrics allows you to answer critical questions like:

• Performance Trending: Is a key performance metric (like revenue, website traffic, or user sign-ups) improving or declining over time?
• Impact Analysis: Did a new feature launch in March cause a spike in user engagement compared to February?
• Pattern Recognition: Do we always see a dip after the holiday season? Understanding seasonality helps with forecasting and planning.

It’s a standard for a reason. MoM analysis gives you a constant pulse on your business's health and the effectiveness of your strategies.

Method 1: The Quickest Way with Table Calculations

Tableau has a built-in feature called "Quick Table Calculations" that makes calculating MoM change incredibly fast. This is the perfect place to start if you need a quick answer.

Let’s assume you want to see the MoM change for your sales data.

Step 1: Set Up Your View

First, get your basic chart in order. Drag your date field (e.g., Order Date) onto the Columns shelf and your measure (e.g., Sales) onto the Rows shelf.

Right-click the Order Date pill in the Columns shelf and select Month. You’ll want the option with the year included, like "MONTH(May 2023)". To get a clean timeline, right-click it again and choose Continuous (this will turn the pill green).

Your view should now look something like a simple line chart showing sales over time.

Step 2: Add the Quick Table Calculation

Now for the speedy part. In the Rows shelf, right-click your SUM(Sales) pill and navigate to Quick Table Calculation > Percent Difference.

Just like that, your line chart changes to show the percentage difference from one month to the next. The first data point will be blank because there’s no prior month to compare it to.

Step 3: Check How the Calculation is Computed

Tableau is usually smart enough to figure out how you want to calculate this. In our example, it calculates the difference along the timeline (Table Across). If your chart were set up differently (e.g., a vertical table), you might need to adjust this. To do so, right-click the same pill again, go to Compute Using, and ensure it’s set to Table (across).

Pros: A fast, easy, no-code way to see MoM changes instantly. Cons: It's tied to this specific view. You can't easily reference this percent change value elsewhere in your workbook.

Method 2: Gaining Flexibility with a Calculated Field

When you need more control or want to reuse your MoM calculation in different charts or dashboards, creating a calculated field is the better approach. The logic is simple: we need to find the sales for the current month and the sales for the previous month, then plug them into the standard percentage change formula: (Current - Previous) / Previous.

Fortunately, Tableau’s LOOKUP() function makes this straightforward.

Step 1: Understand the LOOKUP() Function

The LOOKUP() function is designed to "look" at other rows in your data partition. The syntax is LOOKUP(expression, offset). For our purpose:

• The expression is what we want to look at: SUM([Sales]).
• The offset is how far we want to look. To get the value from the previous period, we’ll use an offset of -1.

Step 2: Create the Calculated Field

• Click the dropdown arrow at the top of the Data pane and select Create Calculated Field.
• Name your field something descriptive, like "MoM Sales % Change".
• Enter the following formula into the box:

(SUM([Sales]) - LOOKUP(SUM([Sales]), -1)) / LOOKUP(SUM([Sales]), -1)

This formula grabs the sales for the current month, subtracts the sales from the previous month (the LOOKUP() part), and then divides that result by the previous month’s sales to get the percentage change.

Note: At the bottom of the calculation dialog box, click "Default Table Calculation" to pre-configure it to compute correctly, or just be mindful of setting the "Compute Using" on the pill as we did in Method 1.

Step 3: Format and Use Your New Field

With the calculation created, right-click it in the Data pane, go to Default Properties > Number Format > Percentage to ensure it always displays as a percentage.

Now, you can drag your "MoM Sales % Change" field onto the Rows shelf, text labels, or color marks of any worksheet. Because this is a reusable field, you can apply it anywhere you need without recreating it.

Visualizing Your Month-Over-Month Data

Numbers in a table are okay, but powerful visuals tell the full story. Here are a few effective ways to visualize your MoM change.

1. Bar Chart with Color

A simple bar chart is excellent for comparing Months. You can make it even clearer by using color to distinguish between growth and decline.

• Set up your view with the continuous Month of Order Date on Columns and your new MoM Sales % Change calculation on Rows.
• This will create a line chart by default. In the Marks card, change the chart type dropdown from "Automatic" to "Bar".
• Drag another copy of your MoM Sales % Change calculation from the Data pane onto the Color tile in the Marks card.
• Click the Color tile, select "Edit Colors," and choose a diverging palette like "Red-Green Diverging." This will automatically color positive MoM changes one color and negative changes another.

2. Dual-Axis Chart for Context

Sometimes, seeing the percentage change isn't enough. A 100% MoM change is fantastic, but is that growth from $1 to $2, or from $50,000 to $100,000? A dual-axis chart combines your raw sales numbers and MoM percentage change in one view.

• Start with your basic line chart of SUM(Sales) over time.
• Drag your MoM Sales % Change calculation onto the opposite side of the Rows shelf. You'll now have two separate charts.
• In the Rows shelf, right-click the MoM Sales % Change pill and select Dual Axis.
• On the Marks card, you now have controls for both measures. Set SUM(Sales) to be a line chart and MoM Sales % Change to be a bar chart. Adjust colors for clarity.
• Finally, right-click on one of the axes and select Synchronize Axis to make sure your chart alignment is accurate.

Common Issues and Quick Fixes

My first data point is always null. How do I fix it?

This is expected behavior because there's no preceding data point in the view to compare against. You have two options:

1. Hide it: Simply right-click the null indicator that appears and select "Hide Indicator". This is the cleanest solution.
2. Make it zero: If you'd prefer to display a "0" instead of a blank, you can wrap your calculation with the ZN() function, which stands for "Zero if Null".

ZN( (SUM([Sales]) - LOOKUP(SUM([Sales]), -1)) / LOOKUP(SUM([Sales]), -1) )

Blue Dates vs. Green Dates (Discrete vs. Continuous)

Remember that Tableau treats blue pills as discrete categories and green pills as continuous values. For MoM growth over time, you almost always want a continuous (green) date pill on your columns shelf. This creates a proper time-series axis rather than just labeling each month as a separate category.

Final Thoughts

Calculating and displaying month-over-month change in Tableau is a core skill that empowers you to track performance and understand trends. Whether you use the quick, one-click table calculation for a fast analysis or build a reusable calculated field for more in-depth dashboards, you're now equipped to answer critical questions about your business's momentum.

Dashboards in Tableau are powerful, but building them takes time and focus that you don't always have. Sometimes you just need an answer fast. That's why we created a tool where you can simply connect your data sources - like Google Analytics, Shopify, or Salesforce - and ask questions in plain English. With Graphed, you can ask, "Show me a bar chart of month-over-month sales change for the last quarter," and get a live, interactive dashboard back in seconds - letting you get insights without the report-building grind.