Sum of variable number of rows

[richzip1]

Hello, I would like to find a formula that will take the total of a column -- but the number of rows in that column will vary.  The attachment hopefully helps to visualize how the totals should be grouped together.

Sum hours 1 (column F):  this is the total of column D, starting from the row that has a value in column B, through the next row with a value in column C.  The next sum starts with the next row that has a value in Column B.  In column F, the sum is populated to the row with a value in column B.

Sum hours 2 (column G):  this is the total of column E, starting from the row that has a value in column B, through the next row with a value in column C.   The next sum starts with the next row that has a value in Column C.  In column G, the sum is populated to the row with a value in column C.

[#2]

@richzip1 

Kind reminder :)from Welcome to your Excel discussion space!:
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(re. your report: the kind of setup that necessarily causes problems when calcs are required)

A Power Query solution attached

[#3 · Accepted solution]

@richzip1 

A formula solution that assumes data are exactly as in your sample

in F2 and copy right then down:

=IF(
    AND(ISNUMBER($B2),ISNUMBER($C2)), D2,
    IF(ISNUMBER($B2), SUM(OFFSET($D2,,COLUMNS($F:F)-1,MATCH(INT($B2), INT($C2:$C15),0))), "")
)

and validate it with CTRL+SHIFT+ENTER (or its equiv on Mac) if you don't run Excel 365/Web

Corresponding sample attached

[#4]

@L z.   Thank you so much! That worked perfectly! Could help with another formula for this same sheet - instead of taking the sum of columns, I would like to calculate the difference between the value in Column C and Column B (the first preceding row with a value in B).

[#5]

@L z.    

Actually I tried the formula above for a larger scale worksheet, and it's not working quite right. In the attached example, F2 should be the sum of D2-D5. However, it's summing all the way down to row 110. If I'm looking at the formula correctly, it's looking for the first row in column C that has the same date as B2.

However, it should only take the sum through the next row where column C has ANY value -- the date does not have to match what's being looked at in column B.

[#6]

@richzip1 

In that case, in F2 and copy in G2 and down:

=IF(
    AND(ISNUMBER($B2),ISNUMBER($C2)), D2,
    IF(ISNUMBER($B2), SUM(OFFSET($D2,,COLUMNS($F:F)-1,MATCH(TRUE,ISNUMBER($C2:$C347),0))), "")
)

For the Elapsed Time in H2 and copy down:

=IF(
    AND(ISNUMBER(B2),ISNUMBER(C2)), C2-B2,
    IF(ISNUMBER(B2), INDEX(C2:C347,MATCH(TRUE,ISNUMBER(C2:C347),0))-B2, "")
)

Both formula to be validated with Ctrl+Shift+Enter if you don't run Excel 365