Conditional SUM using multiple tables in EXCEL

Question

I have a table that I'm trying to populate based on the values of two reference tables.

I have various different projects 'Type 1', 'Type 2' etc. that each run for 4 months and cost different amounts depending on when in their life cycle they are. These costings are shown in Ref Table 1.

Ref Table 1

Month    |  a  |  b  |  c  |  d
---------------------------------
Type 1   |  1  |  2  |  3  |  4
Type 2   |  10 | 20  |  30 |  40
Type 3   | 100 | 200 | 300 | 400

Ref Table 2 shows my schedule of projects for the next 3 months. With 2 new ones starting in Jan, one being a Type 1 and the other being a Type 2. In Feb, I'll have 4 projects, the first two entering their second month and two new ones start, but this time a Type 1 and a Type 3.

Ref table 2

Date    | Jan | Feb | Mar
--------------------------
Type 1  |  a  |  b  |  c
Type 1  |     |  a  |  b
Type 2  |  a  |  b  |  c
Type 2  |     |     |  a
Type 3  |     |  a  |  b

I'd like to create a table which calculates the total costs spent per project type each month. Example results are shown below in Results table.

Results

Date    | Jan | Feb | Mar
-------------------------------
Type 1  |  1  |  3  |  5
Type 2  |  10 |  20 |  40
Type 3  |  0  | 100 | 200

I tried doing it with an array formula:

Res!b2 = {sum(if((Res!A2 = Ref2!A2:A6) * (Res!A2 = Ref1!A2:A4) * (Ref2!B2:D6 = Ref1!B1:D1), Ref!B2:E4))}

However it doesn't work and I believe that it's because of the third condition trying to compare a vector with another vector rather than a single value.

Does anyone have any idea how I can do this? Happy to use arrays, index, match, vector, lookups but NOT VBA.

Thanks

Answer 1

Assuming that months in results table headers are in the same order as Ref table 2 (as per your example) then try this formula in Res!B2

=SUM(SUMIF(Ref1!$B$1:$E$1,IF(Ref2!$A$2:$A$6=Res!$A2,Ref2!B$2:B$6),INDEX(Ref1!$B$2:$E$4,MATCH(Res!$A2,Ref1!$A$2:$A$4,0),0)))

confirm with CTRL+SHIFT+ENTER and copy down and across

That gives me the same results as you get in your results table

If the months might be in different orders then you can add something to check that too - I assumed that the types in results table row labels might be in a different order to Ref table 1, but if they are always in the same order too (as per your example) then the INDEX/MATCH part at the end can be simplified to a single range