To calculate ROI, subtract what you put in from what you got back, divide the result by what you put in, and multiply by 100. If you invested $10,000 and ended with $13,300 after fees and income, your net gain is $3,300 and your return on investment is $3,300 ÷ $10,000 = 33%. The figure tells you how much you earned per dollar invested, but on its own it says nothing about how long it took.
Below is the formula, a full worked example for an investment and for a business project, and the adjustments that make ROI comparable across different time periods.
What is the ROI formula?
- ROI (%) = (Final value + income − total cost) ÷ total cost × 100
“Total cost” should include everything you paid to get the result: the purchase price, commissions, fees and any extra money you added along the way. “Income” covers dividends, interest or rent you received and did not reinvest.
How do you calculate ROI on an investment?
Suppose you bought shares for $10,000 and paid $100 in trading costs. Over three years you collected $400 in dividends, and you sold for $13,000. The math:
- Total cost: $10,000 + $100 = $10,100
- Total returned: $13,000 + $400 = $13,400
- Net gain: $13,400 − $10,100 = $3,300
- ROI: $3,300 ÷ $10,100 ≈ 32.7%
If you ignore the $100 of costs, you get exactly 33%. Small fees rarely change the answer much on one trade, but they add up across many, which is why the SEC’s investor education site stresses checking fees before you invest.
How do you annualize ROI over several years?
A 33% gain in three years is not 11% a year, because returns compound. Use the annualized formula instead:
- Annualized ROI = (Ending value ÷ starting value)^(1 ÷ years) − 1
For the example, (13,300 ÷ 10,000)^(1/3) − 1 ≈ 0.0997, or about 9.97% per year. Compare that with a different investment that gained 20% in a single year: the second one earned more per year even though its total ROI is smaller. Annualizing is the only fair way to compare holdings with different time frames. Our average return calculator handles multi-year sequences, and the compound interest calculator shows how a steady annual rate grows.
How do you calculate ROI on a business project?
The same math works for equipment, software or marketing. Say a bakery buys a $6,000 oven that lets it sell more bread. Over the first year, extra sales bring in $15,000, and the ingredients, packaging and electricity for that extra bread cost $7,500. Gain is $15,000 − $7,500 = $7,500. Subtract the oven:
- Net gain: $7,500 − $6,000 = $1,500
- ROI: $1,500 ÷ $6,000 = 25% in year one
If the oven lasts five years and produces the same gain each year, the project looks far better over its full life. That is why businesses often pair ROI with a payback period (here, $6,000 ÷ $7,500 per year ≈ 0.8 years) and with break-even analysis, which you can run in the break-even calculator.
What counts as a good ROI?
It depends on the risk you took and how long your money was tied up. A useful benchmark is what you could have earned with little or no risk over the same period, such as an insured savings account or a Treasury security. If a risky project returns about the same as a Treasury bill, the risk was not rewarded. The Investor.gov site makes this point repeatedly: higher potential returns come with higher potential losses, and past returns do not guarantee future ones.
Inflation matters too. A 5% annual return with 3% inflation is roughly a 2% gain in buying power. The inflation calculator converts nominal results into real ones.
What mistakes inflate return on investment?
The most frequent errors make a result look better than it was:
- Leaving out fees, taxes, commissions or the cost of your own time.
- Ignoring money added along the way. If you invested another $2,000 halfway through, it belongs in total cost.
- Comparing total returns across different lengths of time instead of annualizing.
- Counting revenue instead of profit on a business project. Sales generated by a campaign are not the gain; the profit on those sales is.
- Cherry-picking the start and end dates.
When cash moves in and out at many different times, a simple percentage gain breaks down and an internal rate of return is the better tool; see the IRR calculator.
Is ROI the same as profit margin?
No. Profit margin divides profit by revenue, so it describes how efficiently sales turn into profit. Return on investment divides profit by the money invested, so it describes how efficiently capital turns into profit. A shop can run a healthy margin and still earn a weak return if it needed a large investment to get there.
How do I calculate it fast?
Enter the amount invested, amount returned and holding period in the ROI calculator. It shows the total return and the annualized figure so you can compare options on equal terms.
How does risk change the way you read ROI?
Two investments can show the same percentage and still be very different choices. One might have moved steadily upward, while the other swung wildly before ending at the same place. The second one could just as easily have finished with a loss, and if you had needed the money at the wrong moment you would have sold at the bottom. A single percentage hides that path.
That is why investors usually look at return alongside risk measures such as how much the value fell from its peak, how concentrated the holding was, and whether the money could be withdrawn when needed. The SEC’s investor education materials recommend matching investments to your time horizon and your tolerance for losses, not to the largest number in a chart.
How should taxes be handled in the calculation?
For a quick comparison, people usually calculate the return before taxes. For a decision you will live with, use after-tax numbers. Gains held in a taxable account may be taxed when you sell, and dividends may be taxed in the year you receive them, while the same holding inside a retirement account is taxed differently. If two options are taxed differently, compare what you actually keep. The IRS explains how capital gains and dividends are taxed in Topic 409.
Sources
- Investor.gov (SEC): Understanding fees
- Investor.gov (SEC): Compound interest calculator
- IRS: Topic 409, Capital gains and losses
- U.S. Bureau of Labor Statistics: Consumer Price Index
FAQ
What does “How to Calculate ROI on an Investment or Project” explain?
To calculate ROI, subtract what you put in from what you got back, divide the result by what you put in, and multiply by 100. If you invested $10,000 and ended with $13,300 after fees and income, your net gain is $3,300…
How should I use this guide with a calculator?
Read the definitions and assumptions first, then open the linked calculator with the same inputs. Treat results as estimates, not professional advice.
Is this financial or medical advice?
No. Calcenzo content is educational. Confirm important decisions with a qualified professional and official sources for your situation.