Forum Discussion
Sumproduct with dates issue
- Sep 19, 2022The problem is that Excel stores dates as numbers. The LEFT function looks at these numbers, not at the formatted dates. Moreover, the result of the comparison is TRUE or FALSE, and SUMPRODUCT ignores such values. Use =SUMPRODUCT(--(TEXT(Sheet1!A2:A1000,"yyyy-mm")=TEXT(C34,"yyyy-mm"))) or =SUMPRODUCT(--(Sheet1!A2:A1000-DAY(Sheet1!A2:A1000)=C34-DAY(C34))) Adjust the range as needed. 
The problem is that Excel stores dates as numbers. The LEFT function looks at these numbers, not at the formatted dates. Moreover, the result of the comparison is TRUE or FALSE, and SUMPRODUCT ignores such values.
Use
=SUMPRODUCT(--(TEXT(Sheet1!A2:A1000,"yyyy-mm")=TEXT(C34,"yyyy-mm")))
or
=SUMPRODUCT(--(Sheet1!A2:A1000-DAY(Sheet1!A2:A1000)=C34-DAY(C34)))
Adjust the range as needed.
=SUMPRODUCT(--(Sheet1!A2:A1000-DAY(Sheet1!A2:A1000)=C34-DAY(C34)))
Working perfectly!