A dynamic sum formula - Excel

Question

Guys I am trying to write a dynamic sum formula where the array range starts from a cut-off date ( this date changes every month ).

I have the periods in the top first row 201801 in A2 , 201802 in B2 etc. and starting from A3 I have the sales' figures.

eg the cut-off date is 201806 , so I need my sum formula to be =sum($F3:L3)

what I was trying to do is =sum(ADDRESS(3,MATCH($B$1,$A$2:$L$2,0),3):L3)

ADDRESS(3,MATCH($B$1,$A$2:$L$2,0),3) returns $F3 which does not work in the sum formula!

Answer 1

INDIRECT is volatile so may not be the best function to use.

I take it that L3 is static, and you're looking to sum from the lookup value to L3 .

• MATCH(201806,$2:$2,0) will return the column number that 201806 first appears in.
• INDEX($3:$3,,6):$L$3 will return a reference to F$3:$L$3 ( F being the sixth column - replace 6 with the MATCH function).
• SUM(F$3:$L$3) adds it all up. Replace F$3:$L$3 with the INDEX .

The final formula would be:

=SUM(INDEX($3:$3,,MATCH(201806,$2:$2,0)):$L$3)  

Replace 201806 with a range reference.

If the end date is variable you can use another INDEX function to find it.
This finds the last date using the MAX function:

=SUM(INDEX($3:$3,,MATCH(201806,$2:$2,0)):INDEX($3:$3,,MATCH(MAX($2:$2),$2:$2,0)))  

This adds from June to December:

=SUM(INDEX($3:$3,,MATCH(201806,$2:$2,0)):INDEX($3:$3,,MATCH(201812,$2:$2,0)))