What is Return on Investment (roi)

Return on investment is a performance measure that can be used to compare several investments. ROI is calculated as net income of an investment divided by the cost of the investment.

ROI = Net income / Investment cost
where
Net Income = Income from the investment - Investment cost

ROI is usually noted as percentage, meaning that 10% of gives us 10 cents per each dollar of investment. If you would like to have ROI as percentage then you should calculate it as:

ROI = (Net income / Investment cost ) x 100.

For example if Net income is 1,200$ and Investment cost is 10,000$, then ROI is 1,200/10,000 = 0.12 or stated as percentage ROI is 12%.

If ROI is negative then the investment should not be considered because the investment is a loss. If ROI is positive then investment is profitable. Higher ROI is better than lower ROI. A project with the highest ROI will have the highest profit rate.

Other measures than money can be used to measure the cost and the income. That is the reason that ROI is very flexible and can be manipulated. Therefore, it is necessary to know how the ROI is calculated, i.e. what are the costs and what are the income? For example, the Accounting ROI is equal to the net income divided by the total assets. ROI works just fine if income and outcome can be easily identified.

ROI can be also used with not so precise definition of income and outcome. One could consider customer satisfaction, accuracy, average shopping chart or something else. For example one could calculate ROI for Customer satisfaction (where CS is short for Customer Satisfaction) like this:

ROI = Change in customer satisfaction / Investment cost
where
Change in customer satisfaction = CS after investment - CS before investment.

What should you do with ROI? First of all, if you have only one investment ROI could only show if your investment is profitable (ROI > 0). If you have several investments and you consider terminating one, probably you should terminate the one with the smallest ROI. Also, if you have several investment opportunities, you should choose the one with the highest ROI. Of course you should consider other factors involved, such as risk, necessary minimum amount for investing, your portfolio...