Tableau Tip: Adding a moving reference line for “today”

Picture a sales chart like this that represents your actual + forecasted sales:

It’s difficult to see where today is in this chart, so you’d like to see it as a reference line on your time axis.  And you want it to be dynamic so that it moves automatically every day.  Ultimately, you want a chart like this and when you look at the chart again in a month, the reference line should be no whatever day that is, October 18 for example.

Step 1: Build the view so that the date field is on the Column shelf and the measure is on the Rows shelf.  Right-click on your date pill and choose Exact Date.

Step 2: Create a calculated field to get today’s date.

Step 3: Add the Today field to the Level of Details shelf.  Right-click on the pill and choose Exact Date.  The pill will turn green, indicating it’s a continuous dimension.

Step 4: Right-click on the x-axis (i.e., time) and choose Add Reference Line.

Step 5: Because the Today field is on the Level of Detail shelf, we can use it as a Reference Line.  Set up the reference line with these settings (format the line as you wish).

That’s it.  The chart looks like this:

If you don’t believe that it works, change the clock on your computer.  Of course, change the clock back when you’re done.

Download the sample workbook here.

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Dan Murray left a great, incredibly useful comment to enhance the chart even more by color-coding actual and forecasted sales.

Step 1: Create a calculated field to determine whether Order Date is less today.

This results in a True/False dimension.

Step 2: Drag the Actual/Forecast dimension onto the color shelf.

Now you have a clear indication of where actuals stop and forecast starts, split exactly by the reference line.

Thanks Dan!