What is the formula for ROI?

Return on Investment (ROI) is calculated as (Gain − Cost) ÷ Cost × 100. Subtract what you originally invested from the current value, divide that gain by the original cost, and multiply by 100 to express it as a percentage. For example, if you invest $10,000 and it grows to $13,000, the ROI is ($13,000 − $10,000) ÷ $10,000 × 100 = 30%.

How do you annualize ROI?

To annualize a multi-year ROI, use the formula: ((Ending Value ÷ Starting Value)^(1 ÷ years)) − 1, then multiply by 100. A 30% total ROI over 2 years annualizes to approximately 14.8% per year, because the gains compound annually rather than adding linearly. Annualized ROI lets you fairly compare investments held for different lengths of time.

Context matters. The S&P 500 has historically returned about 10% per year before inflation, so a long-term stock ROI above that is strong. Real estate ROI often targets 8–12% annually after expenses. For a new business, an annualized ROI above 15% is generally considered good. Always compare ROI against a benchmark like a market index or a risk-free rate, and remember that higher potential ROI usually comes with higher risk.

What are the limitations of ROI?

ROI does not account for the time value of money — a 30% gain over one year is very different from a 30% gain over ten years, but simple ROI treats them the same. It also ignores risk, ongoing costs, opportunity cost, and the timing of cash flows. For a fuller picture, combine ROI with annualized return, internal rate of return (IRR), and net present value (NPV).

How is ROI different from annualized return?

ROI is the total return over the entire holding period, expressed as a percentage of the original investment. Annualized return converts that total into an equivalent per-year rate that accounts for compounding. A 50% ROI over 5 years is roughly an 8.4% annualized return — and annualized return is the better number for comparing investments held for different time spans.

ROI Explained: How to Calculate Return on Investment

Return on Investment — ROI — is one of the most widely used measures in finance, and for good reason: it answers a deceptively simple question in a single number. “If I put money in, how much did I get back relative to what I put in?” Whether you are comparing stocks, weighing a real estate purchase, evaluating a business decision, or judging a marketing campaign, ROI is the common yardstick. This guide walks through the ROI formula, how to annualize returns for multi-year investments, the real limitations of the metric, and worked examples across common asset classes. When you want to skip the arithmetic, an ROI calculator handles any set of numbers instantly.

What is ROI?

ROI measures the profitability of an investment as a percentage of its cost. A positive ROI means you made money; a negative ROI means you lost it. Because ROI is a ratio rather than a dollar figure, it lets you compare investments of very different sizes — a $1,000 stock purchase alongside a $100,000 rental property — on the same scale.

The simplicity of ROI is both its strength and its weakness. It compresses a lot of information into one number, which makes comparison easy, but it also hides details like time horizon, risk, and cash-flow timing. Those limitations matter, and we cover them below — but first, the core formula.

The ROI formula

The basic ROI formula is:

ROI = (Gain − Cost) ÷ Cost × 100

Subtract what you put in (the cost) from what you now have (the gain, or current value), divide that profit by the original cost, and multiply by 100 to turn it into a percentage.

An equivalent way to write the same thing:

ROI = (Current Value − Cost) ÷ Cost × 100

Both forms give the same result — use whichever you find clearer.

A worked example: the $10,000 investment

Suppose you invest $10,000 in a portfolio and two years later it is worth $13,000. Here is the ROI calculation step by step:

Gain = $13,000 (current value) − $10,000 (cost) = $3,000
ROI = $3,000 ÷ $10,000 = 0.30
0.30 × 100 = 30%

Your total ROI over two years is 30%. That is a solid return — but it does not yet tell you how it compares to other opportunities held for different lengths of time. For that, you need to annualize.

Annualized ROI: accounting for time

A 30% total return over two years sounds impressive, but is it 15% per year? Not quite — because investment returns compound. Each year’s gains earn their own gains the next year. To find the per-year rate that, compounded over the holding period, would produce your total ROI, you annualize it.

The annualized ROI formula is:

Annualized ROI = ((Ending Value ÷ Starting Value)^(1 ÷ years)) − 1

Then multiply by 100 to get a percentage.

Using the previous example:

Ending ÷ Starting = $13,000 ÷ $10,000 = 1.3
Exponent: 1 ÷ 2 years = 0.5
1.3^0.5 ≈ 1.1418
1.1418 − 1 = 0.1418
0.1418 × 100 ≈ 14.18%

So a 30% total ROI over two years is about a 14.8% annualized return (the slight difference comes from rounding). The key insight: annualized returns are always lower than the naive “total divided by years” figure when returns are positive, because compounding does part of the work.

Annualized ROI is the right metric whenever you compare investments held for different periods. A 30% gain in two years is not the same as a 30% gain in ten years — the first is roughly 14.8% per year, the second closer to 2.7%. An ROI calculator handles the exponent math automatically.

Real estate ROI

Real estate ROI involves two moving parts: appreciation (the property going up in value) and rental income (cash flow while you hold it). A simplified example:

Purchase price: $250,000
Down payment and closing costs: $60,000 total investment
Five years of net rental income after expenses: $30,000
Sale price after five years: $310,000

Total gain = ($310,000 − $250,000) + $30,000 = $90,000. ROI = $90,000 ÷ $60,000 × 100 = 150% over five years. Annualized: (($310,000 + $30,000) ÷ $60,000)^(1/5) − 1, which works out to roughly 20% per year — though this simplified example ignores taxes, maintenance surprises, and mortgage interest, all of which can materially reduce the real return.

Real estate investors often use cap rate (annual net operating income ÷ property value) and cash-on-cash return (annual cash flow ÷ cash invested) alongside ROI to capture these nuances.

Stock market ROI

For stocks, ROI usually means total return — price appreciation plus dividends. The S&P 500 has historically returned about 10% per year before inflation, and roughly 7% after inflation. A diversified investor in low-cost index funds can use that long-run average as planning anchor.

Suppose you invest $5,000 in an S&P 500 index fund and reinvest dividends. After eight years it is worth $10,000. Total ROI = ($10,000 − $5,000) ÷ $5,000 × 100 = 100%. Annualized: (10,000 ÷ 5,000)^(1/8) − 1 ≈ 9.05% per year — right in line with the long-run historical average.

For new investors, services like Betterment automate diversified index investing with automated rebalancing, while a full-service broker like Fidelity offers both index funds and individual securities for hands-on portfolios. Run any projected investment through an ROI calculation before committing, so the comparison is apples-to-apples.

Business and project ROI

Businesses use ROI to evaluate projects: new equipment, a marketing campaign, a software rollout. Here the “cost” is the total project spend, and the “gain” is the additional revenue or cost savings attributable to the project.

Marketing campaign cost: $20,000
Attributed revenue: $80,000
ROI = ($80,000 − $20,000) ÷ $20,000 × 100 = 300%

A 300% ROI sounds spectacular, but two caveats apply. First, you need a reliable way to attribute revenue to the campaign — otherwise you may credit it with sales that would have happened anyway. Second, time still matters: 300% over one year is very different from 300% over five years. This is why annualized ROI and internal rate of return (IRR) are often preferred for business cases.

Limitations of ROI

ROI is useful precisely because it is simple — but that same simplicity hides several important factors:

Time is ignored. A 30% gain over one year and a 30% gain over ten years look identical in raw ROI. Annualized ROI corrects this.
Risk is ignored. A 20% ROI from a volatile startup and a 20% ROI from a government bond are not equivalent — one carries far more risk of total loss.
Cash-flow timing is ignored. Inflows that arrive early can be reinvested; inflows that arrive late cannot. Metrics like IRR and net present value (NPV) account for this; ROI does not.
Ongoing costs can be understated. If you exclude taxes, fees, maintenance, or inflation, ROI is artificially high. Always include all relevant costs in the denominator.
Opportunity cost is hidden. A 5% ROI is only “good” relative to what else you could have done with the money. Compare against a benchmark — an index return, a savings rate, or a risk-free Treasury yield.

A more complete view combines several metrics: ROI for a quick headline number, annualized ROI to compare timeframes, IRR for cash-flow timing, and NPV for absolute dollar value after discounting. An ROI calculator can be a starting point — but for material decisions, look at the full picture.

How to use ROI well

Always include all costs: the original purchase price plus fees, taxes, transaction costs, and ongoing expenses.
Be consistent with gains: include dividends and cash flow, not just price appreciation.
Annualize for fair comparison: never compare total ROIs across different time horizons.
Compare to a benchmark: a stock ROI should be compared to a relevant market index; a real estate ROI to typical cap rates; a business ROI to the company’s cost of capital.
Account for risk: adjust expected ROI upward for riskier investments, or weight it by the probability of success.

The bottom line

ROI tells you, in one number, how much you gained relative to what you invested: (Gain − Cost) ÷ Cost × 100. It is the universal yardstick for comparing investments across stocks, real estate, and business projects. Its chief weakness is that it ignores time, risk, and cash-flow timing — which is why annualized ROI matters for any multi-year holding, and why specialized metrics like IRR and NPV exist for complex decisions. Use a 30% total return over two years as a working benchmark example (about 14.8% annualized), include every relevant cost, and always compare your return to a sensible benchmark before declaring an investment a success.