title: How do I count cell values in one column using a criteria of another column in Excel?
body: <p>I have X,Y data in two columns (A,B) of an Excel spreadsheet. I want to count the values in the B column using a criteria of the A-column. Specifically, the A,B column data are dates and occurrences of an event on that given day. But I want the counts based on each week, not each day (column E in the image). COUNTIF won't work but was wondering how this can be accomplished. As you can see in the spreadsheet, there are two occurrence for the week of 9/30/2018 to 10/6/2018 (1 event each on 10/3 and 9/30), so in cell F2 we have 2.</p>
  
  <p><a href="https://i.stack.imgur.com/wITqJ.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wITqJ.jpg" alt="Need Formula to count by week"></a></p>