Return on investment measures how much money you made or lost on what you spent

Return on investment (ROI) is a calculation that shows whether money you put into something came back to you with a gain or a loss. It answers one question: for every dollar I invested, how many cents did I gain or lose? The formula is straightforward: subtract what you started with from what you ended with, divide by what you started with, then multiply by 100 to get a percentage.

ROI works the same way whether you invested in stocks, real estate, a business, or anything else. A positive ROI means you made money. A negative ROI means you lost money. The higher the percentage, the better the return. The calculation itself takes two minutes once you have the numbers in front of you.

Key Takeaways

  • ROI is calculated by dividing your gain or loss by the amount you invested, then multiplying by 100 to express it as a percentage.
  • A 20% ROI means that for every $100 you invested, you gained $20; a -10% ROI means you lost $10 per $100 invested.
  • ROI does not account for how long your money was tied up, so comparing two investments requires knowing the time period for each.
  • ROI works for any type of investment — stocks, rental property, a business, or a side project — as long as you know the starting amount and ending amount.

The ROI formula and how to use it

The formula is: (Ending Value − Starting Value) ÷ Starting Value × 100 = ROI %

Here is a concrete example. You buy 100 shares of a stock at $50 per share, so you invest $5,000. Two years later, you sell all 100 shares at $65 per share, receiving $6,500. Your gain is $6,500 − $5,000 = $1,500. Divide $1,500 by $5,000 to get 0.30. Multiply by 100 to get 30%. Your ROI is 30%.

Another example: you buy a rental property for $200,000. After five years of collecting rent and paying expenses, you sell it for $220,000. Your gain is $20,000. Divide $20,000 by $200,000 to get 0.10. Multiply by 100 to get 10%. Your ROI is 10% over those five years.

Negative ROI works the same way. If you invested $10,000 and it is now worth $8,500, your loss is −$1,500. Divide −$1,500 by $10,000 to get −0.15. Multiply by 100 to get −15%. Your ROI is −15%.

Why time matters when comparing investments

ROI as a percentage does not tell you how long your money was invested. This matters because a 20% return over one year is much better than a 20% return over ten years. To compare two investments fairly, you need to know the time period for each one.

If Investment A gave you a 15% ROI over two years and Investment B gave you a 15% ROI over five years, they have the same ROI percentage, but Investment A was more efficient with your money. Investment A returned your capital faster, so you could have reinvested it sooner.

When you are comparing investments, write down the ROI and the number of years side by side. Some investors calculate an annualized return — the average return per year — to make comparisons easier. That calculation is more complex, but the basic idea is the same: shorter time periods for the same return are better.

What ROI does not tell you

ROI is a useful number, but it has limits. It does not account for risk. An investment that returned 50% might have been extremely risky and could have lost everything. An investment that returned 8% might have been very safe. ROI alone does not tell you which is which.

ROI also does not include costs that happened along the way. If you bought a rental property and paid property taxes, maintenance, insurance, and property management fees, those reduce your actual profit even if the ROI calculation looks good on paper. Make sure you subtract all real expenses before you calculate the gain.

ROI does not account for inflation either. If you invested $10,000 ten years ago and it is now worth $12,000, your ROI is 20%. But if inflation was 3% per year over that period, your money did not actually grow as much as the percentage suggests. The purchasing power of that $12,000 is less than it would have been if inflation had not happened.

ROI for different types of investments

The ROI formula works the same way for stocks, real estate, business investments, and personal projects. The difference is in what counts as your "starting value" and "ending value."

For stocks, the starting value is what you paid for the shares, and the ending value is what you sold them for (or what they are worth today if you still own them). For rental property, the starting value is what you paid for the property, and the ending value is what you could sell it for today, plus any net rental income you collected. For a business, the starting value is what you invested, and the ending value is the business's current value or what you sold it for.

Some investors also include dividends or rental income in their ROI calculation. If a stock paid you $200 in dividends while you held it, add that $200 to your ending value before you calculate. If a rental property generated $15,000 in net income over five years, add that to the sale price before you calculate. This gives you a more complete picture of what the investment actually returned.

Comparing ROI across different time periods

If you want to compare two investments that had different holding periods, you can annualize the ROI. This means converting the total return into an average annual return. The calculation is more involved, but the idea is simple: it shows you how much the investment returned per year on average.

For example, if Investment A returned 30% over three years, the annualized return is roughly 9% per year. If Investment B returned 20% over one year, the annualized return is 20% per year. Now you can see that Investment B was actually more efficient, even though the total ROI percentage was lower.

You do not need to calculate annualized returns for every investment. But when you are deciding between two options or reviewing your own performance over time, knowing the annual average helps you make better comparisons.

Common mistakes when calculating ROI

The most common mistake is forgetting to subtract all expenses. If you bought a stock and paid a $50 trading commission, subtract that from your starting value or add it to your cost basis. If you sold a rental property and paid a 6% realtor commission, subtract that from your sale price. These costs reduce your actual profit.

Another mistake is using the wrong starting or ending value. For a stock, use the price you actually paid, not the price it was trading at when you decided to buy. For real estate, use the price you actually paid, including closing costs, not the asking price. For a business, use the cash you actually invested, not the valuation someone gave you.

A third mistake is comparing ROI percentages without looking at the time period. A 50% return over five years is not as good as a 50% return over one year, but the percentage alone does not show that difference. Always write down the time period alongside the ROI.

Frequently Asked Questions

Is a 10% ROI considered good?

It depends on the type of investment and how long you held it. The stock market has historically returned about 10% per year on average over long periods, so a 10% annual return is considered reasonable for stocks. For bonds or savings accounts, 10% would be very good. For a business or real estate, 10% might be low or high depending on the risk and the time period. Compare your ROI to similar investments and to inflation.

How do I calculate ROI if I invested money multiple times?

If you added money to an investment over time, the calculation becomes more complex. The simplest approach is to calculate ROI for each separate investment and then average them. A more accurate method is to use a weighted average that accounts for how long each chunk of money was invested. For most people, tracking each investment separately and calculating ROI for each one is clearer than trying to combine them into one number.

Should I include taxes in my ROI calculation?

Taxes reduce your actual profit, so yes, you should account for them if you want to know what you really made. If you sold an investment and owed $5,000 in capital gains taxes, subtract that from your gain before you calculate ROI. This gives you your after-tax return, which is what actually matters to you. Many investors track both the pre-tax and after-tax ROI to see the full picture.

Can ROI be more than 100%?

Yes. If you invested $1,000 and it grew to $3,000, your ROI is 200%. This happens with some stocks, real estate, or business investments over long periods. It can also happen with leveraged investments where you borrowed money to invest. A 200% ROI means your money tripled, which is excellent but also usually means higher risk was involved.