Return on investment (ROI) is a ratio between net profit (over a period) and cost of investment (resulting from an investment of some resources at a point in time). A high ROI means the investment's gains compare favorably to its cost. As a performance measure, ROI is used to evaluate the efficiency of an investment or to compare the efficiencies of several different investments.^[1] In economic terms, it is one way of relating profits to capital invested.

In business, the purpose of the return on investment (ROI) metric is to measure, per period, rates of return on money invested in an economic entity in order to decide whether or not to undertake an investment. It is also used as an indicator to compare different investments within a portfolio. The investment with the largest ROI is usually prioritized, even though the spread of ROI over the time period of an investment should also be taken into account. Recently, the concept has also been applied to scientific funding agencies’ (e.g., National Science Foundation) investments in research of open source hardware and subsequent returns for direct digital replication.^[2]

ROI and related metrics provide a snapshot of profitability, adjusted for the size of the investment assets tied up in the enterprise. ROI is often compared to expected (or required) rates of return on money invested. ROI is not time-adjusted (unlike e.g. net present value): most textbooks describe it with a "Year 0" investment and two to three years’ income.

Marketing decisions have an obvious potential connection to the numerator of ROI (profits), but these same decisions often influence assets’ usage and capital requirements (for example, receivables and inventories). Marketers should understand the position of their company and the returns expected.^[3] In a survey of nearly 200 senior marketing managers, 77 percent responded that they found the "return on investment" metric very useful.^[3]

Return on investment may be extended to terms other than financial gain. For example, social return on investment (SROI) is a principles-based method for measuring extra-financial value (i.e., environmental and social value not currently reflected in conventional financial accounts) relative to resources invested. It can be used by any entity to evaluate the impact on stakeholders, identify ways to improve performance and enhance the performance of investments.

As a decision tool, it is simple to understand. The simplicity of the formula allows users to freely choose variables, e.g., length of the calculation time, whether overhead cost is included, or which factors are used to calculate income or cost components. To use ROI as an indicator for prioritizing investment projects is risky since usually the ROI figure is not accompanied by an explanation of its make-up.

For long-term investments, the need for a Net Present Value adjustment is great.^[4] Similar to Discounted Cash Flow, a Discounted ROI should be used instead.

One of greatest risks associated with the traditional ROI calculation is that it does not fully "capture the short-term or long-term importance, value, or risks associated with natural and social capital"^[5] because it does not account for the environmental, social and governance performance of an organization. Without a metric for measuring the short- and long-term environmental, social and governance performance of a firm, decision makers are planning for the future without considering the extent of the impacts associated with their decisions.

For a single-period review, divide the return (net profit) by the resources that were committed (investment):^[3]

or

or

Complications in calculating ROI can arise when real property is refinanced, or a second mortgage is taken out. Interest on a second, or refinanced, loan may increase, and loan fees may be charged, both of which can reduce the ROI, when the new numbers are used in the ROI equation. There may also be an increase in maintenance costs and property taxes, and an increase in utility rates if the owner of a residential rental or commercial property pays these expenses.

Complex calculations may also be required for property bought with an adjustable rate mortgage (ARM) with a variable escalating rate charged annually through the duration of the loan.

Marketing not only influences net profits but also can affect investment levels too. New plants and equipment, inventories, and accounts receivable are three of the main categories of investments that can be affected by marketing decisions.^[3] According to a recent study, business partnerships with "micro-influencers" can bring a greater ROI than collaborations with big celebrities.^[6]

RoA, RoNA, RoC, and RoIC, in particular, are similar measures with variations on how 'investment' is defined.^[3]

ROI is a popular metric for heads of marketing because of marketing budget allocation. Return on Investment helps identify marketing mix activities that should continue to be funded and which should be cut.

First introduced by blockchain platform Radium Core ^[10] , the Spread Fees Protocol is a new approach to the classic Proof of Stake architecture for receiving a network reward in exchange for securing the network. Blockchain networks are maintained by many different individuals and each of these nodes deserves a little extra reward whenever someone records new data into the SmartChain ^[11] . Historically, transaction fees were included as a reward in the block in which the transactions resided. The SFP dictates that this could be unfair, as wallets with more coins would be more likely to receive these blocks with higher rewards.  With the spread fee protocol, fees are awarded back to the stakers slowly, over the subsequent 1440 blocks rather than all at once, ensuring that no one powerful staker can capture all the rewards. Most blocks that are staked will have a reward slightly higher than the stated block reward, which is a result of this protocal. The more the network is used, and as more transactions are sent, the extra rewards from spread fees will increase proportionally.

To address the lack of integration of the short and long term importance, value and risks associated with natural and social capital into the traditional ROI calculation, companies are valuing their environmental, social and governance (ESG) performance through an Integrated Management approach to reporting that expands ROI to Return on Integration.^[7] This allows companies to value their investments not just for their financial return but also the long term environmental and social return of their investments. By highlighting environmental, social and governance performance in reporting, decision makers have the opportunity to identify new areas for value creation that are not revealed through traditional financial reporting.^[8] The social cost of carbon is one value that can be incorporated into Return on Integration calculations to encompass the damage to society from greenhouse gas emissions that result from an investment. This is an integrated approach to reporting that supports Integrated Bottom Line (IBL) decision making, which takes triple bottom line (TBL) a step further and combines financial, environmental and social performance reporting into one balance sheet. This approach provides decision makers with the insight to identify opportunities for value creation that promote growth and change within an organization.^[9]