Although it is virtually impossible to establish an exact calculation of this figure is likely to facilitate the evaluation of the ROI of your campaign. To do this, take the revenue from sales, subtract that amount of advertising costs, then divide the result by the total advertising costs.
(Revenue-Cost) / Cost
For example, suppose you want to attract visitors to your website to generate sales of its articles, which would mean a profit of 10 euros per item sold. Spent $ 1,000 on his campaign last week, and as a result has sold 130 items. Revenues from sales or total profit is $ 1300 ($ 10 profit multiplied by 130 units). Therefore, the remaining 1,000 euros for the cost of your advertising campaign of 1300 euros of profit, which gets 300 euros. This amount of benefits that are recovered as a result of its initial advertising investment of 1,000 euros. Your ROI, expressed as a percentage of your initial investment would be 30% (300/1.000 multiplied by 100).