Question

How do I create a timeline slicer that allows users to view overlapping events?
I need a timeline slicer in Power BI that enables users to filter and view overlapping events, such as project phases or campaign periods. The slicer should allow selecting a date range while ensuring that events spanning multiple dates remain visible. What is the best way to implement this using Power BI’s native slicers or a custom approach with DAX?

Answer 1

Creating a timeline slicer in Power BI for visualizing events that are overlapping takes a series of steps described thus:

1. Create a Date Table

Create a completely dedicated date table with a continuous date range. There will be a relationship between the date table and your event table based on the event's start date or end date.

2. Create a Range Slicer for the Date

Introduce a date range slicer that can be selected from the date table so that users can choose a range. Make sure to set it in Between mode so that it allows the user flexibility.

3. Create DAX Measure for Overlap Events

Adopt a measure that would tell which events fall within the selected range: 

ShowEvent =  
VAR SelectedStart = MIN('DateTable'[Date])  
VAR SelectedEnd = MAX('DateTable'[Date])  

RETURN  
IF(  
    MAX(Events[StartDate]) <= SelectedEnd &&  
    MAX(Events[EndDate]) >= SelectedStart,  
    1,  
    0  
)

4. Apply a Visual-Level Filter

• Add this measure to your event table visuals (table, matrix, Gantt chart, etc.).
• Filter the visual to show only rows where ShowEvent = 1.