How to calculate CPC based on ROI?

I am extremely bad @ mathematics so excuse me for this stupid question.

I tried to figure it out but after 10 minutes i gave up.

Ok here is goes:

Let's say i have a EPC of $0.50 and i want to get atleast a 50% ROI.

How do i calculate what my maximum CPC may be?

Thanks in advance....

 

If you have an EPC of $0.50, and you're looking for an ROI of 50%, then you're max CPC would be about $0.33.

 

Could you tell me please how you got to that number so i can calculate it myself. Thanks

 

Well since you only gave me those two numbers (and no payout), I just did it in my head.

$0.25 CPC with an EPC of $0.50 means 100% ROI.

$0.50 CPC with an EPC of $0.50 means 0% ROI.

So for 50% ROI, the CPC has to be midway between .25 and .50. That means the CPC will be $0.33.

 

OK, but i would like to know the formula, because i can't do it in my head with this example:

I want a 76% ROI and my EPC is $0.83

What CPC do i need here?

I need a formula to calculate this one.

- Thanks.

 

You need to give me the payout of the offer you're running.

 

$3.80 for example.