Return on Investment Calculator
This return on investment calculator shows how much your money has grown, as a percentage of what you first put in. Enter the amount you invested and the amount you got back, or what it is worth now. If you also know how many years you held the investment, you can see the return per year as well.
The results are useful for comparing one investment with another, or for checking how a past investment performed. The calculator works only from the figures you enter, so the answer is only as accurate as those figures. For decisions about property, loans or savings, check the numbers with your lender or bank.
How to use the return on investment calculator
- Enter the amount you invested in the first box, in pounds.
- Enter the amount you got back, or what the investment is worth now, in the second box.
- If you know how long you held the investment, enter the number of years in the third box. This is optional.
- Press the calculate button to see your return on investment as a percentage.
- Read your gain in pounds to see the difference between what you put in and what you have.
- If you entered the years held, check the per year (annualized) figure to compare investments held for different lengths of time.
The formula
- ROI = (amount back − amount invested) ÷ amount invested × 100
- Per year = ((amount back ÷ amount invested) ^ (1 ÷ years) − 1) × 100
Worked example
The figures below are made up to show the maths. They are not current prices, rates or product figures.
| Amount invested | £10,000.00 |
|---|---|
| Amount you got back (or it is worth now) | £13,000.00 |
| Years held | 3 years |
- Return on investment 30.00%
- Gain £3,000.00
- Per year (annualized) 9.14%
Tips for an accurate answer
- Use the same currency and the same kind of amount for both boxes, so the comparison is fair.
- Decide whether the amount back includes any fees, charges or tax, and be consistent about it.
- Include all money you put in, such as later top-ups, if you want a true picture of the return.
- For a time-based figure, enter the full number of years held, including part years where you know them.
- Check the final numbers with your bank, broker or lender before making any financial decision.
Questions people ask
What is the formula for ROI return on investment?
ROI is worked out by taking the amount back, subtracting the amount invested, and dividing the result by the amount invested, then multiplying by 100. This calculator does that for you once you enter the two amounts. In the example, £10,000.00 invested and £13,000.00 back gives 30.00%.
Can I work out a monthly return on investment with this calculator?
This calculator works out the return per year when you enter the years held. It does not give a monthly figure directly. You can enter the time in years, using a fraction of a year where you know it, to get the annualized result.
What does the return on investment percentage tell me?
It shows the gain or loss as a percentage of the amount you invested. In the example, £10,000.00 invested and £13,000.00 returned gives a return on investment of 30.00%. This makes it easier to compare investments of different sizes.
Does the calculator include fees or tax?
The calculator does not add or remove fees or tax by itself. It uses only the figures you type in. If you want the return after costs, enter the amount you actually received after those costs.
Why is the per year figure lower than the total return?
The total return is spread across all the years you held the investment. In the example, a 30.00% total return over 3 years gives a per year (annualized) figure of 9.14%, because the growth compounds each year.
Can I use this for investments that are still running?
Yes. Enter what the investment is worth now in the second box. The result will then show the return so far, but it will change if the value changes.
Is this calculator financial advice?
No. It is a calculator that works out the maths of return on investment. Check the figures with your lender, bank or a qualified adviser before making any decision about money.
Sources
This calculator uses the standard loan and interest formulas above and the numbers you type. It needs no outside figures.
An estimate from the numbers you enter, worked out with the formula shown. It is maths, not financial advice: your lender or bank has the final figures. Page checked 23 Oct 2026. Read the disclaimer