Here’s a complete calendar in Excel using the following formula.

=IF(MONTH(DATE(YEAR(A1),MONTH(A1),1))<>MONTH(DATE(YEAR(A1),MONTH(A1),1)-

(WEEKDAY(DATE(YEAR(A1),MONTH(A1),1))-1)+{0;1;2;3;4;5}*7+{1,2,3,4,5,6,7}-1),””,

DATE(YEAR(A1),MONTH(A1),1)-(WEEKDAY(DATE(YEAR(A1),MONTH(A1),1))-1)+{0;1;2;3;4;5}*7

+{1,2,3,4,5,6,7}-1)

This is the first edition. Each month is on a separate worksheet.  After revisiting this, I forgot how to do arrays in Excel.  Follow theses steps in order for this code to work if you were to start from scratch.

1. Click on cell A1 and type in a date like: 1/1/2010
2. Click on cell A2 and highlight 7 columns to the right and 5 rows going down
3. Paste in the code above in the formula bar for A2
4. Hold down CTRL and Shift on the keyboard and press Enter
5. Format the dates as you please

Excel calendar