For this example, let's assume the following...

1) Three month's worth of data

1) A1:E3 contains the data

2) First row contains your headers/labels

3) C2:E3 contains your monthly values to sum

4) A10 contains the month number of interest, such as 1

5) B10 contains the year of interest, such as 2006

Try the following formula...

=SUMPRODUCT(SUBTOTAL(9,OFFSET($C$2:$E$3,ROW($C$2:$ E$3)-MIN(ROW($C$2:$E$3)
),DATEDIF(DATE($B$2:$B$3,$A$2:$A$3,1),DATE(B10,A10 ,1),"M"),1,1)))

....which requires that you enable the Analysis ToolPak add-in...

Tools Add-In and check Analysis ToolPak

Hope this helps!

In article ,
J_Barn wrote:

I need to sum values by month/year (Ex: Jan 2006) based on data that I've set
up in an Excel spreadsheet.

My spreadsheet is set up in this fashion.
StartMonth : StartYear: Month1 : Month2 : Month3 : ...Month24
12 : 2005: 400 : 250 : 1000 : etc
1 : 2006 : 300 : 650 : 2500 : etc

Based on the Start Month and Start Year values, I want to sum the
appropriate figures into a Grand total for that particular month.

In this instance, Jan 2006 should = 550, Feb 2006=1650, Mar 2006=2500

Does anyone have a solution to this? I'm in desperate need of some help.
Thank you.