Formatting Issues

How to Stop Excel from Removing Hyphens in Windows Date Formats

Phi Hung Vo Sep 28, 2026 870 views

Question details

The user wants to stop Excel and Outlook from stripping literal hyphens from Windows ISO date formats (yyyy-MM-dd).

How to Fix Office Apps Removing Hyphens from Windows ISO Date Formats

Product: Microsoft Excel and Outlook
Device & OS: Windows
Scenario: Opening CSV files or entering dates into Office applications after configuring the Windows regional date format to an ISO standard (yyyy-MM-dd).
Observed behavior: The Office applications recognize the date sequence from the system clock but fail to preserve the literal hyphens, causing the dates to display incorrectly without the intended punctuation.

Before you start

Verify that your Windows regional date settings are correctly configured to the yyyy-MM-dd format before attempting to adjust settings within individual Office applications.

Solution 1Recommended

Apply a Custom Date Format in Excel

Use the Format Cells feature to manually define a custom date format, ensuring hyphens are strictly preserved.

By default, Excel may try to adapt system dates to its own regional locale presets. Applying a custom format explicitly forces Excel to display the exact date structure you require.

Select the Target Cells

Highlight the cells, columns, or rows containing the dates that are missing hyphens.

Open Format Cells

Right-click the selected area and choose 'Format Cells' from the context menu, or press the Ctrl + 1 keyboard shortcut.

Set Custom Format

Navigate to the 'Number' tab and select 'Custom' from the category list. In the 'Type' input field, type 'yyyy-mm-dd' and click OK to apply the changes.

Format Applied: This method ensures that your dates will maintain their hyphens regardless of underlying regional default changes.

Solution 2

Adjust the Excel Locale Setting

Change the locale applied to the specific cells to a region that natively supports the desired date format.

Solution 3

Test in Safe Mode to Rule Out Add-ins

Run Excel in Safe Mode to determine if a third-party add-in is interfering with how dates are parsed and displayed.

Format Dates Easily in WPS

Easily Manage Date Formats with WPS Spreadsheet

Avoid frustrating formatting changes by using WPS Spreadsheet. It offers precise control over cell formatting, allowing you to easily apply and retain ISO date formats like yyyy-mm-dd without unexpected modifications.

1. Open Your File: Launch WPS Spreadsheet and open your CSV or spreadsheet file containing the dates.
2. Select and Format: Highlight the date cells, right-click, and select 'Format Cells' (or press Ctrl+1).
3. Apply Custom ISO Format: Navigate to the 'Custom' category, type 'yyyy-mm-dd' in the Type box, and click OK to lock in the hyphenated format.

Free to use with a familiar, user-friendly interfaceFully compatible with Microsoft Excel (.xlsx) and CSV formatsPrecise custom cell formatting options to retain hyphens and specific date layouts

microsoft office alternative - wps office

Frequently Asked Questions

Why does Excel change my CSV date formats when I open them?

Excel automatically parses date-like strings in CSV files using its default formatting rules and your system's locale settings. This automated parsing can sometimes strip hyphens or change the date sequence to match localized presets instead of retaining the literal text.

Is there a central setting to force Office to use Windows date formats exactly?

While Office apps generally inherit Windows regional settings, certain default cell behaviors in Excel will prioritize their own localized date sequences. Applying a Custom Format (yyyy-mm-dd) within the document is the most reliable workaround.

Will repairing Microsoft Office fix date formatting issues?

If Excel is malfunctioning or failing to respect locale changes entirely, running an Office Repair (via Windows Settings > Apps > Modify) can resolve corrupted installation files. However, it will not change default CSV parsing behaviors.

Document & File Issues