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Investment Return Calculator UK
Calculate simple return, net gain or loss, approximate annualised return and the effect of contributions and fees on investment performance.
Simple return
Annualised estimate
Fees included
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Calculate your investment return
Enter the money invested, final value, period and fees. The calculator updates automatically and estimates both simple and annualised return.
Amount invested at the start.
Regular money added during the period.
Current or ending investment value.
Number of years the investment was held.
Platform, fund, advice or dealing fees paid during the period.
How to use this calculator
- Enter the initial investment and any monthly contributions.
- Enter the final value of the investment.
- Add the number of years and any fees paid.
- Review the net gain, simple return and approximate annualised return.
What your investment return means
Simple return compares the net gain or loss with the total amount invested. It is useful for a quick view of overall performance.
Annualised return estimates the average yearly return over the investment period. This makes it easier to compare investments held for different lengths of time.
Important: this calculator is a performance estimate. It does not account for every tax rule, exact contribution date, dividend reinvestment date or dealing cost.
Review where your investments sit
Compare investment returns with ISA, pension and compound growth calculators to understand performance in context.
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How investment returns work
Investment return measures how much an investment has gained or lost compared with the money invested. The simplest version is the gain divided by the amount contributed.
That simple figure can be useful, but it does not always tell the full story. A 40% return over two years is very different from a 40% return over twenty years, which is why annualised return matters.
When monthly contributions are involved, the calculation becomes more complex because not all money was invested for the full period. This calculator uses an approximate IRR-style method to estimate the annualised return.
If an investment is held inside a Stocks and Shares ISA, gains are normally tax-free. If it is held outside a tax wrapper, gains may interact with Capital Gains Tax.
What affects your investment return
- Starting investment: the amount invested at the beginning affects the return calculation.
- Monthly contributions: regular contributions change the timing of invested cash.
- Final value: the current or ending value determines the gain or loss.
- Fees: charges reduce your net return and can have a larger effect over time.
- Investment period: annualised return depends heavily on how long the investment was held.
- Inflation: a positive nominal return can still be weak if inflation has reduced real value.
Investment return calculator formula
The calculator shows simple return directly and uses an approximate monthly IRR method when regular contributions are included.
total_contributed =
starting_investment + monthly_contribution × months
net_gain =
final_value - total_contributed - fees
simple_return =
net_gain ÷ total_contributed
If there are no monthly contributions:
annualised_return =
(final_value ÷ starting_investment)^(1 ÷ years) - 1
If monthly contributions are included:
estimate monthly IRR using cashflows
annualised_return =
(1 + monthly_IRR)^12 - 1
Simple return vs annualised return
These two figures answer different questions. Simple return shows the total result. Annualised return spreads the result across time.
| Measure | What it tells you | Best used for |
|---|---|---|
| Simple return | Total gain or loss compared with money contributed. | Quick performance snapshot. |
| Annualised return | Approximate average yearly return. | Comparing investments held for different time periods. |
| Net gain | Final value minus contributions and fees. | Seeing the actual pound-value gain or loss. |
Investment return calculator FAQs
What is investment return?
Investment return is the gain or loss made compared with the amount invested, usually shown as a percentage.
What is annualised return?
Annualised return estimates the average yearly return over the investment period, which helps compare investments held for different lengths of time.
Does this calculator include fees?
Yes. Fees entered into the calculator reduce the net gain and estimated return.
Can investment return be negative?
Yes. If the final value is lower than the amount invested plus fees, the calculator shows a negative return.
Is the annualised return exact with monthly contributions?
It is an approximate IRR-style estimate. It is useful for planning, but not a replacement for an exact performance report from a platform or adviser.
Key terms used in this calculator
These glossary pages explain the main terms used when comparing investment performance and tax wrappers.