What Is Return on Investment (ROI)?
Return on investment, or ROI, measures how much profit you earn relative to the amount you invested. It is expressed as a percentage and is one of the quickest ways to compare different opportunities. An ROI calculator uses the basic formula: ROI equals final value minus cost, divided by cost, then multiplied by 100.
A positive ROI means you made money, while a negative ROI means you lost money. Because ROI is a ratio, it works across very different projects. You can use it to compare a rental property against a stock purchase, or a marketing campaign against another advertising channel, as long as you track the total cost and the resulting value.
ROI vs Annualized Return
A common mistake is confusing ROI with annualized return. ROI does not account for how long an investment was held. Earning 50% over ten years is very different from earning 50% in a single year. The annualized return, or compound annual growth rate (CAGR), smooths the result over the holding period so you can compare investments of different lengths fairly.
The CAGR formula raises the ratio of final value to cost to the power of one divided by the number of years, then subtracts one. This gives a single yearly rate that reflects the effect of compounding. Including both ROI and annualized return in your analysis prevents you from overestimating a slow-growing investment.
Why ROI Matters Across Different Assets
In real estate, ROI includes purchase costs, repairs, taxes, and rental income. In marketing, ROI compares the revenue generated against campaign spend. In the stock market, ROI helps you judge whether a trade beat a simple benchmark. Knowing the ROI alone does not tell the whole story, but ignoring it makes it nearly impossible to know whether a project was worth the effort.
For long-term planning, pair this with our investment calculator and our compound interest calculator.