ROI Calculator – Return on Investment Percentage
Use this ROI calculator to compare the net profit or loss from an investment with its original cost. It gives a simple percentage return, which is useful for checking a project, purchase, campaign, or other one-time investment on a consistent basis.
ROI Calculator
How to use the ROI calculator
- Enter the total investment cost, including any costs you want the comparison to reflect.
- Enter the net profit earned. This is the amount left after subtracting the investment cost and relevant expenses from the final value or proceeds.
- Select calculate to see the simple return on investment as a percentage.
If the investment made a loss, enter a negative profit. For example, enter -500 if the loss was £500 or $500. Use the same currency for both inputs; the percentage result does not depend on which currency you use.
ROI formula
ROI = (net profit ÷ investment cost) × 100
Net profit can also be calculated as final value minus the original investment and any costs you decide to include. A positive result indicates a gain; a negative result indicates a loss.
Worked example
Suppose an investment cost £10,000 and was later worth £12,000 after relevant expenses. The net profit is £2,000. The calculation is (£2,000 ÷ £10,000) × 100, giving a simple ROI of 20%.
Simple ROI versus annualised return
Simple ROI does not show how long it took to earn the return. A 20% gain over one year and a 20% gain over five years have the same simple ROI but very different rates of growth. When comparing investments held for different periods, an annualised return may be more informative.
For an investment with no additional deposits or withdrawals, a common annualised-return formula is: (ending value ÷ beginning value)1 ÷ years − 1. Multiply the result by 100 for a percentage. This page’s calculator reports simple ROI, not annualised return.
What the result does not include automatically
- The time taken to earn the return
- Uneven cash flows, additional deposits, or withdrawals
- Fees, tax, maintenance, financing costs, or inflation unless you include them in net profit
- The risk taken to achieve the return
- Whether an investment is suitable for your circumstances
There is no single percentage that is “good” for every investment. A useful comparison should consider the holding period, costs, liquidity, risk, and an appropriate alternative. Historical or projected returns are not guarantees of future results.
Sources and review information
For background on measuring returns and investment risk, see the US Securities and Exchange Commission’s Investor.gov explanations of annual return and investment risk. These sources are educational; rules and tax treatment vary by country.
Last reviewed: 17 August 2026. Calculations are for general information and estimation only, not financial, tax, or investment advice. See our editorial policy for how calculator content is checked.