I have a range and need to sum it using SUM function but the result is N/A if there is any N/A value. How can I make the SUM function to treat the N/A value as 0 value? Please help!
Use Array Formula
=SUM(IF(ISNA(A1:A4),0,A1:A4))
Press Ctrl+Shift+Enter after entering the formula
Note: Replace A1:A4
with your range

1+1: A nice improvement on my solution  no need to modify the original data. – Mike Fitzpatrick Aug 11 '10 at 6:57

1Nice. Never thought of using an array formula. I was happy with using =SUMIF(A1:A4, "<>#N/A") until I discovered it breaks if the spreadsheet is opened in a copy of Excel localised for another language! Unfortunately replacing "<>#N/A" with "ISNA()" doesn't work, but the array formula is a nice multilingual solution. Sadly, it's not a suitable approach for the same challenge with AVERAGEIF() … :( – Joe Carroll May 27 '14 at 14:48


Thanks @wilson ! When I considered it briefly I didn't think of using "" instead of zero, silly me :) Using zero affects the sample size, of course, which led me to dismiss the solution, but empty cells are simply ignored. – Joe Carroll May 29 '14 at 11:20

Does not work with the magical Cr@pXcel 2013, but answer below (=aggregate) works like charm! – user221741 Mar 17 '16 at 12:29
The easiest way:
Use SUMIF
the value > 0.
So the syntax for that one is
=SUMIF(A1:B2, "> 0")
You will get the same result since it will ignore any nonnumeric or 0 values.

2

1Could do
=SUMIF(A1:B2, ">=0") + SUMIF(A1:B2, "<0")
to include negative numbers. I suspect that would be faster than the accepted array formula solution, if performance is a concern. – kizzx2 Dec 11 '12 at 1:46
There is a new function in Excel which will add all the values either positive or negative while ignoring NA's.
=aggregate(9,6, range of your data)
9 is used for sum while 6 is for ignoring all NA's. There are other options, as well, beside addition. For example, you can do product, standard deviation, and so on.
More information on AGGREGATE here.
Use SUBTOTAL instead:
=SUBTOTAL(9,A1:A50)
You can convert the #N/A to zeros in your source range and then use the normal SUM function:
=IF(ISNA(OriginalFormula), 0, OriginalFormula)

2Since office 2007 there's a new feature,
IFERROR
, and then it can look like this:=IFERROR(OriginalFormula,0)
making it much nicer. – Michael Oct 15 '12 at 10:21 
If there are formulas I'd copy as numbers, replace #N/A in column with 0 and then sum as usually
This way it seems to work:
SUMIF(range;"<>#N/A";range)
Not so robust but effective!