Formatting Issues

Fix Excel Date and Time Format Changes After Saving and Reopening

Aamir Naveed Akram Oct 13, 2026 870 views

Question details

The user needs to prevent Excel from automatically changing date and time formats after saving and reopening a workbook.

Product: Microsoft Excel
Device & OS: Windows
Scenario: Saving and reopening an Excel workbook containing specific date and time formats.
Observed behavior: Excel automatically alters the previously set date and time formats of cells upon reopening the file, often reverting to system defaults.

Before you start

Check if the issue happens in just one specific workbook or across all newly created Excel files to determine if you are dealing with a file-specific corruption or a system-wide setting.

Solution 1Recommended

Adjust Windows Regional Date and Time Settings

Excel often defaults to the system's regional settings. Correcting these settings ensures Excel interprets and displays dates accurately when reopening files.

Windows controls the default short and long date formats used by Microsoft Office applications. If these settings are misconfigured or were recently changed by a system update, Excel may revert your custom formats to match the system default upon reopening.

Open Regional Settings

Open the Windows Control Panel, change the view to 'Large icons' or 'Small icons', and select 'Region'.

Adjust Formats

Under the 'Formats' tab, review the 'Short date' and 'Long time' formats. Use the dropdown menus to select your required layout.

Apply and Restart

Click 'Apply' and then 'OK'. Close all active Excel windows and restart the application to see if the default formatting is resolved.

Adjust Windows Regional Date and Time Settings

System-Wide Change: Modifying Windows regional settings will alter the default date and time displays for all applications on your computer, not just Excel.

Solution 2

Apply Specific Custom Cell Formatting

Manually forcing a custom format in Excel can override automatic changes caused by default cell styles.

Solution 3

Repair the Microsoft Office Installation

If formatting issues persist across all files despite correct regional settings, your Office installation might be corrupted and require a repair.

Reliable Date Formatting

Format Dates and Times Easily with WPS Spreadsheet

Avoid frustrating formatting glitches by managing your data in WPS Spreadsheet. It offers a highly compatible and stable environment for standard and custom date formats, ensuring your data looks exactly how you saved it.

1. Open Your File: Launch WPS Office and open your existing spreadsheet file.
2. Select and Format: Highlight the cells you want to format, right-click, and select 'Format Cells'.
3. Apply Date Format: Under the 'Number' tab, click 'Date' or 'Custom' to set your precise time format, then click 'OK'.
4. Save Securely: Save your document. WPS Spreadsheet securely locks in your cell formats so they remain consistent upon reopening.

Highly stable cell formatting that retains your date and time settings after saving.Fully compatible with Microsoft Excel (.xlsx, .xls) file formats.Familiar user interface makes it easy to apply and manage custom number formats.Free, lightweight, and fast spreadsheet alternative for everyday data analysis.

microsoft office alternative - wps office

Frequently Asked Questions

Why do dates change to numbers like 44200 in Excel?

Excel stores dates as sequential serial numbers so they can be used in calculations. For example, 44200 represents a specific number of days since January 1, 1900. If the cell format reverts to 'General' instead of 'Date', you will see this raw serial number.

Does saving an Excel file as CSV change the date format?

Yes, saving a file as a CSV (Comma Separated Values) saves only the raw text and strips out custom formatting. When you reopen the CSV, Excel applies default formats based on your system's regional settings, which may alter how dates are displayed.

How can I prevent Excel from automatically formatting numbers as dates?

To stop Excel from converting specific inputs (like fractions or hyphenated numbers) into dates, type an apostrophe (') before the number, or pre-format the target cells as 'Text' before entering your data.

Can a corrupted workbook cause formatting issues?

Yes, file corruption can lead to inconsistent cell formatting, missing styles, or formatting resetting to defaults upon reopening. Copying the data into a brand-new workbook often resolves corruption-related formatting issues.

Document & File Issues