How do I create a formula that will return a date where the sum of it and previous dates are greater-CodePudding

CodePudding user response：

This is a model built around your having 20 weeks so that you can have one formula which doesn't require continuous adjustment - it does require one column of helper cells for each week, though:

the helper cells start in column Y, where the formula in Y2 is

=SUM($C2:C2)

which is then copied to the right as far as column AR, and then copied down, one row for each of your products. With all of the helper cells populated, the array formula in W2 is

=IFNA(INDEX($C$1:$V$1,MATCH(1,N((Y2:AR2-B2)>0),0)),"In the future")

which is then copied down, one row for each of your products.