How to find subtotals in variable positions.

I have a series of columns of numbers which need subtotalling. The places to subtotal are blank cells. There is is always a constant number of these but they can be at any point in the column. I am looking for a formula I can use in an adjacent column.
I hope the attached worksheet will make this clearer.
John

In G4 copied down
=IF(F4="",SUM(F$4:F4)-SUM(G$3:G3),"")

1. Are you sure your formulas make sense: the totals are different in each scenario: first time not including blank cell, second time including blank cell, third time omitting the first value??? This looks like inconsistent logic to me.
2. Once clarified, I can have a look. But overall I would advise to change the layout of your data. It appears to me you need overly complex formulas because your data is arranged in a bad way.

Regards

@oeldere

RaulSerg is not the OP, but a helper. If he/she was the OP then I would have been the only helper & so no need to specify who they are replying to.

Easily done.

@fluff, RaulSerg, oeldere
Thankyou! With a small change to the data list and the use of SUMIF you have enabled me to solve my problem.
I hope that a few Reputation points and a "Thread Solved" will calm the little storm that I seem to have provoked. Ill never understand "Your correct wrong treath" or that it is evidently "Easily done"
Regards
John

You're welcome & thanks for the feedback.

There was no "little storm" oeldere, simply said that the post i was querying had been made to the wrong thread. Which is easily done if you have multiple tabs running.