Incorrect Gantt Tooltip Dates

[Wluka]

Hello, I have an odd problem with a Gantt chart in Power BI. 

My data table shows the data and time, is correctly formatted as date/time – yet when this is shown in Gantt view, the tooltips do not show the correct end date and time, instead defaulting to 24 hours later. It also converts from DD/MM/YYYY to MM/DD/YYYY. 

Source table: 

Gantt visualisation data fields: 

Tooltip display: 

Has anyone experienced this before and know of any possible solutions? 

Thanks! 

[v-pnaroju-msft]

Hi Wluka,

We wanted to see if the information we gave helped fix your problem. If you need more help, please feel free to contact the Microsoft Fabric community.

Thank you.

[v-pnaroju-msft]

Hi Wluka,

We are following up to see if what we shared solved your issue. If you need more support, please reach out to the Microsoft Fabric community.

Thank you.

[v-pnaroju-msft · Accepted solution]

Hi Wluka,

Thank you for the update.

Based on my understanding of the scenario and the provided screenshots, the observed behavior occurs because the Microsoft Gantt visual treats End Dates as exclusive and defaults to US date formatting in tooltips.

Please find attached the screenshot and a sample PBIX file, which may assist in resolving the issue:

Kindly ensure that the date columns are typed as Date/Time. Create formatted columns using FORMAT() and add these fields to the Tooltips bucket of the Gantt visual. The tooltip will then display the exact Start and End dates and times without the 24hour shift and in the same date format as the source.

We hope the information provided helps to resolve the issue. Should you have any further queries, please feel free to contact the Microsoft Fabric community.

Thank you.

[v-pnaroju-msft]

Thankyou, @anilgavhane and @Shahid12523 for your responses.

Hi Wluka,

We appreciate your inquiry through the Microsoft Fabric Community Forum.

We would like to inquire whether have you got the chance to check the solutions provided by @anilgavhane and @Shahid12523 to resolve the issue. We hope the information provided helps to clear the query.
Should you have any further queries, kindly feel free to contact the Microsoft Fabric community.

Thank you.

[Wluka]

Hello, thanks all – sadly no breakthroughs yet – I have tried most of these things so far, but still facing the same challenges. 

[Shahid12523]

- Wrong End Date: Gantt tooltips often add +24h if the task ends at the same time next day (e.g., 9 AM to 9 AM).
- Date Format Flip: Tooltips default to MM/DD/YYYY, ignoring your locale.
- Fixes:
- Use FORMAT() in DAX to create custom tooltip fields.
- Convert datetime to text for tooltips.
- Check duration logic to avoid rounding errors.
- Set Power BI regional settings to your preferred locale.

[anilgavhane]

What's Causing the Issue

1. Tooltip Date Format Conversion
   The Gantt visual often defaults to US-style MM/DD/YYYY formatting in tooltips, even if your model or system locale is set to DD/MM/YYYY. This is due to how the visual renders tooltips independently of Power BI’s global formatting settings.
2. End Date Showing +24 Hours
   This usually happens when:

• The Gantt visual interprets the end date as exclusive rather than inclusive.
• The time component is missing or defaulted to 00:00:00, causing the visual to assume the task ends at the start of the next day.

Workarounds and Fixes

1. Explicitly Format Dates as Text

Create new columns using DAX to format your dates exactly as you want:

FormattedStartDate = FORMAT([StartDate], "DD/MM/YYYY HH:mm") FormattedEndDate = FORMAT([EndDate], "DD/MM/YYYY HH:mm")

Then use these columns in the tooltip field instead of the raw date/time fields. This bypasses the visual’s internal formatting logic.

2. Adjust End Date by Subtracting a Minute

If the end date is being interpreted as the next day, try subtracting a small time increment:

AdjustedEndDate = [EndDate] - TIME(0,1,0)

This keeps the date within the expected range without affecting your actual data logic.

3. Check Locale Settings

Ensure your Power BI Desktop or Service is set to the correct regional locale (e.g., UK for DD/MM/YYYY). You can find this under:

• Power BI Desktop: File > Options > Regional Settings
• Power BI Service: Settings > Language and Region

4. Use a Custom Tooltip Page

If the built-in tooltip is too rigid, create a custom tooltip report page with full control over formatting. Then assign it to your Gantt visual under Visual > Tooltip > Report Page.