Calculate daily averages in a pivot table with weekly or other irregular periodic data

[Charles Bushby]

If I have this data in a list how do I calculate the average daily sales using weekly totals. The pivot table would give a result of 5.35 for January but I reckon it should be 4.42. Furthermore if the sales data were not weekly but irregular how would I then calculate the average daily sales?

Any help with this would be most appreciated.

Charles Bushby

Date	Sales per week
29-Dec-19​	40​
05-Jan-20​	50​
12-Jan-20​	30​
19-Jan-20​	20​
26-Jan-20​	50​
02-Feb-20​	2​

 

[Charles Bushby]

I should add that I am trying to show the data by grouping monthly in a pivot table to show daily sales per month