Rednax

[(Gross/Cost)-1]*100 = % ROI

Example... grossed $10, cost $6.75... 48% ROI (you spent $6.75 to make $3.25)

I suppose you're maybe not looking for ROI... margin of profit is $3.25?

Net profit/Revenue (3.25/10) = .325 *100 = 32.5%