Formula for Auto Fill Day Names in Excel

 

It was a problem I faced. Tried to find the solution and now sharing here for the knowledge of those who will also needs in future. 

Yes, you can easily auto-fill day names (like Mo, Tu, We, etc.) across columns in Excel or Google Sheets using a formula instead of manually typing each one.

✅ Here's a step-by-step solution:

Assuming:

• You want to start from July 1, 2025, which is a Tuesday.

• You want to fill the day initials like Tu, We, Th... across columns.

• The first day (1 July) will be in column B (or whichever column you prefer).

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✅ Excel / Google Sheets Formula

Paste this formula in the first cell (e.g., B1) and drag it horizontally to the right for all 31 days of July:

=TEXT(DATE(2025,7,COLUMN(A1)),"ddd")

If you want 2-letter abbreviations instead of 3 (e.g., Tu instead of Tue), use:

=LEFT(TEXT(DATE(2025,7,COLUMN(A1)),"ddd"),2)

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🔁 How it works:

• DATE(2025,7,COLUMN(A1)): Creates July 1, 2025 in the first column, then July 2, 3, etc. as you move right.

• TEXT(...,"ddd"): Converts the date into a day name (e.g., Tue).

• LEFT(...,2): Gets only the first 2 letters (Tu).

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✅ Bonus Tip:

If you want dates in the second row (like 1, 2, 3...) and day names in the first row, just put:

• Row 1 (Day): Use above formula.

• Row 2 (Date): =COLUMN(A1) or =COLUMN()-1 depending on starting column.