Calculate sum for a date range - excel

Question

I'd like to calculate the sum of multiple values for a range of overlapping dates. It should return the sum for a specific year and split the values that fall into more than one year proportionally.
Example:
╔══════════╦════════════╦════════════╗
║ Value ║ From ║ To ║
╠══════════╬════════════╬════════════╣
║ 100,00 € ║ 01.01.2015 ║ 31.12.2015 ║
║ 150,00 € ║ 01.07.2015 ║ 31.06.2016 ║
║ 300,00 € ║ 01.01.2016 ║ 31.12.2016 ║
╚══════════╩════════════╩════════════╝
Expected result for year 2015: 175,00 €
Expected result for year 2016: 375,00 €
I did't find an efficient way using SUMIF() or SUMIFS(). Especially for splitting the result proportionally for overlapping dates.

Answer 1

I am suggesting the use of helper columns, with the column headers being the years for which the totals will be calculated i.e. 2015 and 2016.
I have added an extra row to the data to make sure that it works when the time period is not a whole year.
The area of overlap is the smaller of the higher ends of the two date ranges minus the larger of the lower ends of the two date ranges. If this turns out to be negative then there is no overlap and the result should be set to zero. This gives rise to the following formula for each row starting in E2:-
=MAX((MIN(DATE(E$2,12,31),$C3)-MAX(DATE(E$2,1,1),$B3))+1,0)
where the first column header is in E2.
However with the data given in the question, this produces an inexact answer because there are more days in the second 6 months of the year than in the first
6 months.
If you work in whole months using the following formula you can get an exact answer:-
=MAX((MIN(E$2*12+12,YEAR($C3)*12+MONTH($C3))-MAX(E$2*12+1,YEAR($B3)*12+MONTH($B3)))+1,0)
Then work out the total overlap for each time period in G3:-
=E3+F3
And calculate the proportion of spending as Amount X Overlap for year / Total overlap in H3:-
=$A3*E3/$G3
The method can readily be extended to arbitrary date ranges, not just whole years.
Working in days:-
Working in months:-
Here is an array formula (must be entered with Ctrl-Shift-Enter) which will do the calculation in one step, but it seems rather long. In a production version, $C3:$C6 would be replaced by $C:$C etc. :-
=SUM(IF(IF(E$2*12+12<YEAR($C3:$C6)*12+MONTH($C3:$C6),E$2*12+12,YEAR($C3:$C6)*12+MONTH($C3:$C6))-IF(E$2*12+1>YEAR($B3:$B6)*12+MONTH($B3:$B6),E$2*12+1,YEAR($B3:$B6)*12+MONTH($B3:$B6))+1>0,IF(E$2*12+12<YEAR($C3:$C6)*12+MONTH($C3:$C6),E$2*12+12,YEAR($C3:$C6)*12+MONTH($C3:$C6))-IF(E$2*12+1>YEAR($B3:$B6)*12+MONTH($B3:$B6),E$2*12+1,YEAR($B3:$B6)*12+MONTH($B3:$B6))+1,0)*$A3:$A6/(YEAR($C3:$C6)*12+MONTH($C3:$C6)-YEAR($B3:$B6)*12-MONTH($B3:$B6)+1))
The two methods (helper columns and array formula) would give different results for date ranges that fell partly outside the years 2015 and 2016 e.g. 1/7/14-30/6/15 would put the full amount into 2015 the first way but only half of it the second way.

Answer 2

Thank you very much for your answer, Tom.
This is what I ended up with.
╔═══════╦════════════╦════════════╦══════╦══════╗
║ Value ║ From ║ To ║ 2015 ║ 2016 ║
╠═══════╬════════════╬════════════╬══════╬══════╣
║ 100 ║ 01.01.2015 ║ 31.12.2015 ║ 175 ║ 375 ║
║ 150 ║ 01.07.2015 ║ 30.06.2016 ║ ║ ║
║ 300 ║ 01.01.2016 ║ 31.12.2016 ║ ║ ║
╚═══════╩════════════╩════════════╩══════╩══════╝
Using the following formular were Value is A, From is B, To is C
=ArrayFormula(
SUM(
IFERROR(
IF(
IF(
D$1 * 12 + 12 < YEAR($C:$C) * 12 + MONTH($C:$C);
D$1 * 12 + 12;
YEAR($C:$C) * 12 + MONTH($C:$C)
)
- IF(
D$1 * 12 + 1 > YEAR($B:$B) * 12 + MONTH($B:$B);
D$1 * 12 + 1;
YEAR($B:$B) * 12 + MONTH($B:$B)
) + 1 > 0;
IF(
D$1 * 12 + 12 < YEAR($C:$C) * 12 + MONTH($C:$C);
D$1 * 12 + 12;
YEAR($C:$C) * 12 + MONTH($C:$C)
)
- IF(
D$1 * 12 + 1 > YEAR($B:$B) * 12 + MONTH($B:$B);
D$1 * 12 + 1;
YEAR($B:$B) * 12 + MONTH($B:$B)
) + 1;
0
)
* $A:$A / (
YEAR($C:$C)
* 12 + MONTH($C:$C)
- YEAR($B:$B)
* 12 - MONTH($B:$B)
+ 1
)
; 0
)
)
)
Hint: You can post the formular indented to Google Spreadsheets to keep it readable.