Entering Dates Every 7 Days Using a Formula in Excel

1. Enter the first date in the cell where you want the series to begin. For example, enter 12/20/2009 in cell A1.
2. In the cell below the first date (cell A2), enter the formula
   Formula:

   =A1+7 

   and press Enter. This formula adds 7 days to the date in cell A1.
3. Now, select cell A2 and drag the fill handle (the small square at the bottom right corner of the cell) down to the cells where you want the series to end. Excel will automatically fill in the dates every 7 days.
4. If you want to customize the date format, select the cells with the dates and right-click. Choose Format Cells and select the desired date format from the Number tab.

That's it! Your dates will now be entered every 7 days using a formula in Excel.