How to calculate how many more units/hours needed to meet a percentage.

[kooladakim]

Hi! How do I calculate how many more “flagged” hours are needed to meet a percentage goal?

I get a bonus at the end of every month if I meet my 80% rate.

For example, I (always) work 40 hours every week. I am assign projects and I have to flag how many hours it takes me to complete it. If my flagged hours compared to my actual work hours is 80% or more completed I get a bonus.

In sample attached, in my 4th week how many flag hours would I need to meet my 80% overal?

 

[BadgerRoad]

B6 is total hours worked, E6 is goal (80%)
So, formula would be B6*E6-SUM(C2:C4)
You would need 78 hours to reach the goal!

Book1
	A	B	C	D	E
1	Week #	Hours Worked	Hours Flagged	Current Rate %	Goal
2	1	40	20	50%
3	2	40	10	25%
4	3	40	20	50%
5	4	40	78	195%
6	Sub Total	160	128	80%	80%
Sheet1

Cell Formulas
Range	Formula
D2:D6	D2	=C2/B2
C5	C5	=B6*E6-SUM(C2:C4)
B6:C6	B6	=SUM(B2:B5)