Reference lines in Tableau - Step-by-Step Guide

Introduction

Reference lines help you add a line on your chart to show important values like averages or targets. They make it easier to compare your data against a fixed point or summary measure.

When you want to show the average sales on a sales chart to see which months are above or below average.

When you need to highlight a sales target line on a bar chart to compare actual sales against the goal.

When you want to mark a specific date on a timeline to show an event or deadline.

When you want to add a constant value line to a scatter plot to separate data into groups.

When you want to show minimum or maximum values as a guide on your chart.

Steps

Step 1: Open

- Tableau worksheet with your chart

Your chart is visible and ready for editing

Step 2: Right-click

- the axis where you want to add the reference line

A context menu appears

Step 3: Select

- "Add Reference Line" from the context menu

The Add Reference Line dialog box opens

Step 4: Choose

- "Reference Line" tab in the dialog box

Options to set the reference line appear

Step 5: Set

- "Value" dropdown to select a measure or constant

The reference line will be based on the selected value

Step 6: Customize

- Label, Line, and Tooltip sections in the dialog

You see the preview of the reference line on the chart

Step 7: Click

- "OK" button

The reference line appears on the chart at the chosen value

Before vs After

Before

Chart shows monthly sales bars with no lines to indicate average or targets

After

Chart shows monthly sales bars with a solid reference line at the average sales value labeled 'Average'

Settings Reference

Value

📍 Add Reference Line dialog box, Value dropdown

Defines the value or calculation where the reference line will be placed

Default: Constant

Label

📍 Add Reference Line dialog box, Label section

Controls the text shown on or near the reference line

Default: Value

Line Style

📍 Add Reference Line dialog box, Line section

Changes the appearance of the reference line

Default: Solid

Tooltip

📍 Add Reference Line dialog box, Tooltip section

Controls whether a tooltip appears when hovering over the reference line

Default: Show

Common Mistakes

Adding a reference line on the wrong axis

The line will not align with the data you want to highlight and can confuse viewers

Always right-click the axis that corresponds to the measure or dimension you want to reference

Choosing 'Constant' but not entering a value

The reference line will not appear because Tableau does not know where to place it

Enter a specific number when using 'Constant' as the value

Not customizing the label, leaving it blank

Viewers may not understand what the reference line represents

Add a clear label like 'Target' or 'Average' to explain the line

Summary

Reference lines add clear markers on charts to highlight important values or targets.

You add them by right-clicking the axis and selecting 'Add Reference Line'.

Make sure to choose the correct axis and value to avoid confusion.