Transforming data from Monthly to Weekly buckets

Hi all

I have several years of forecast data on item and market level and in Monthly buckets – more than 30 000 rows.
I want to transform the data into weekly buckets.
I cannot find an effective way of doing this in Excel.

Use the link below to see my sample data with the input and output I want to achieve .

https://drive.google.com/open?id=0Bx...zE4ZGVPdDZFNmM


I hope someone is able to help me out on this or give some guidance.

What is the weekly pattern: your file is 4,4,5,4,5,4 for months to June rather than a more predictable 4,4,5 .

Using Glenn's formula for 4,4,5

=SUMIFS(E:E,A:A,H24,B:B,I24,C:C,J24,D:D,--LEFT(K24,6))/IF(MOD(MID(K24,5,2)+0,3)=0,5,4)

Thank you all

I can use your formula, Glenn.
I was also hoping for getting a formula for the Week output like 20170101, 20170102, 20170103 etc.
I did this just manually in the sample.
But your formula for getting the data laid out on weeks works nicely.
Thank you.