ROI Calculator Formula: How to Calculate ROI

This calculator works out the return on investment (ROI) as a percentage. You enter the initial cost of an investment and the final value it returned, and the calculator gives you the ROI percentage plus the net profit or loss. The standard formula is ROI = (Final Value − Initial Cost) ÷ Initial Cost × 100.

Formula

In words: ROI equals the net profit (final value minus initial cost) divided by the initial cost, then multiplied by 100 to get a percentage.

Symbols:

• ROI – return on investment, expressed as a percentage (%)
• Final Value (F) – the total amount you receive or the current value of the investment, in dollars ($)
• Initial Cost (C) – the total amount you paid to acquire the investment, in dollars ($)

ROI = ((F − C) / C) × 100

Worked Example

Using the default values from the calculator above: initial cost = $1,000, final value = $1,200.

1. Net profit = Final Value − Initial Cost = $1,200 − $1,000 = $200
2. Divide net profit by initial cost: $200 ÷ $1,000 = 0.2
3. Multiply by 100 to get a percentage: 0.2 × 100 = 20%

The calculator shows ROI = 20.00% and net profit = $200.00, which matches the manual calculation.

When to Use ROI

ROI is a universal metric used to evaluate the efficiency of an investment. You can use it for:

• Comparing different investment opportunities (stocks, real estate, business projects)
• Evaluating marketing campaigns (cost of campaign vs. revenue generated)
• Assessing equipment purchases or operational improvements
• Measuring the performance of a portfolio over time

The key benefit of ROI is its simplicity – it gives a single number that can be compared across different types of investments, regardless of size.

How to Read the Result

A positive ROI means the investment made money; a negative ROI means it lost money. A 20% ROI on a $1,000 investment means you gained $200, or 20 cents for every dollar invested. However, ROI alone doesn’t tell you how long the investment took. A 20% ROI over 1 year is very different from 20% over 10 years. For time-sensitive comparisons, you need annualized ROI or CAGR (Compound Annual Growth Rate).

Common Mistakes and Misconceptions

• Forgetting to include all costs – transaction fees, taxes, maintenance, and other expenses should be subtracted from the final value or added to the initial cost. The formula only works if both numbers are complete.
• Mixing up the order – always do (Final − Initial) ÷ Initial, not (Initial − Final) ÷ Initial. The latter gives a negative result for a profitable investment.
• Ignoring time – a 50% ROI over 5 years is roughly 8.4% per year, not 10% per year (due to compounding). Use annualized ROI for fair comparisons.
• Using net profit instead of final value – if you enter the profit as the final value, you’ll get a wildly inflated ROI. The final value must be the total amount you end up with, not just the gain.

Limits of the Formula

The basic ROI formula has several limitations:

• No time dimension – it doesn’t account for how long the investment was held.
• No risk adjustment – a high ROI might come with high risk; ROI doesn’t reflect that.
• Cash flow timing – for investments with multiple cash flows (e.g., rental income), simple ROI ignores when those cash flows occur. Internal Rate of Return (IRR) or Net Present Value (NPV) are better for those cases.
• Inflation – a nominal ROI of 5% during 4% inflation is only a 1% real return.

Frequently Asked Questions

What is a good ROI?

There’s no universal benchmark. A “good” ROI depends on the risk, the industry, and the time horizon. Generally, stock market average returns are around 7-10% per year before inflation, but that’s a long-term average. For marketing campaigns, many businesses aim for 300-500% ROI (or more), but that’s because marketing costs are lower and risks are different. Compare ROI to your alternative investment options and the risk you took.

How do I annualize ROI?

To annualize ROI, use the formula: (1 + ROI)^(1/n) − 1, where n is the number of years. For example, a 50% ROI over 3 years: (1.5)^(1/3) − 1 ≈ 0.1447, or 14.47% per year. This accounts for compounding and gives a fair comparison across different time periods.

Can ROI be negative?

Yes. If the final value is less than the initial cost, the ROI is negative, indicating a loss. For example, buying a stock for $500 and selling it for $400 gives an ROI of −20%. Negative ROI is a clear signal that the investment didn’t pay off.

What’s the difference between ROI and profit?

Profit (or net profit) is the absolute dollar amount gained: Final Value − Initial Cost. ROI is that profit expressed as a percentage of the initial cost. Profit tells you how much you made; ROI tells you how efficiently you made it. A $100 profit on a $100 investment is a 100% ROI, while the same $100 profit on a $1,000 investment is only 10% ROI.

Should I include taxes and fees in the calculation?

Yes, for an accurate ROI, include all costs associated with buying and selling. For example, if you buy a house for $200,000 and pay $5,000 in closing costs, your initial cost is $205,000. Similarly, subtract selling costs (commissions, fees) from the final sale price. The more complete your numbers, the more meaningful your ROI.

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in c | Initial cost | $ | 1000 | 0
in f | Final value | $ | 1200 | 0
out roi | ROI | % | ((f - c) / c) * 100 | 2
out profit | Net profit | $ | f - c | 2